After 90 games Stockfish leads 32-18 with 40 draws. Stockfish won 3 game pairs and extended its lead to 14 wins. The 3 game pair wins were all long endgames where Stockfish saw the win many moves ahead and Leela was still unsure, and Stockfish played with minimal time available. Since there are only 10 games left Stockfish will win the match. Leela hasn't won a pair in the last 26 pairs.
Games 81-82 started with a 20-ply sideline in the Sicilian Richter-Rauzer variation. The engines castled in opposite directions, there was one pawn exchange and all pieces were on the board. In game 81 the engines exchanged minor pieces, a pawn exchange opened the d file. The black queen moved forward on the king side and came back, both engines moved their major pieces to the center. Evals increased for a while, Leela's eval was over 1.5 on move 25. Stockfish thought Leela's move was a mistake and its eval dropped. In a series of exchanges the engines reduced to a QN vs QN position, Leela's eval came down as well. The engines traded pawns and created a white passer on the queen side and a black passer on the king side. Both passers raced forward, both were stopped. Leela captured a pawn but evals were low and the game was adjudicated.
In game 82 the engines repeated game 81 for 13 plys, the d file was open. Evals increased while Leela doubled rooks on the d file. A white knight blocked the file but in a series of exchanges the knight was exchanged as well as a pair of rooks. The game reached a QRB vs QRN position on move 24, the engines opened the f file as well.
Stockfish moved its major pieces forward, Leela pushed the h pawn to avoid back rank threats. Stockfish moved its rook to the back rank and exchanged rooks. The engines traded pawns and created two white passers on the queen side and two black passers on the king side. Both engines pushed a passer forward, Stockfish captured a pawn in the center and it seemed Leela was winning the race. Leela captured the white passer and its passer was on the 2nd rank, but Stockfish captured the black knight with check, it saw the win in its PV.
It didn't seem possible for Stockfish to stop the queening as well as protect its bishop, but Stockfish was confident it could. The first set of checks ended with the white queen on g2 and Stockfish protected its bishop with the b pawn. Leela didn't have a check, next move Stockfish connected its bishop and queen on the long diagonal to prevent a queening, giving Leela a pawn. Leela gave a few checks and the white king moved forward. Stockfish pushed the black king back and the white queen moved to the 7th rank. It allowed the queening in the end, before mating. Stockfish wins the game pair, it leads 28-16.
Games 83-84 started with a rare 20-ply sideline in the Pirc defense, classical variation. All pawns and pieces were on the board, white had a space advantage. In game 83 there was a pawn exchange in the center, then a pair of knights were exchanged. Evals came down, on move 21 Leela gave a knight for a pawn and created connected passers on the queen side. Leela captured another pawn on the queen side, then a third pawn to open the d file. In a series of exchanges the engines reduced to a RB vs RRB position, Leela was down a rook but up 3 pawns. For a long while the engines mainly shuffled and made some pawn moves. On move 72 Stockfish gave a pawn, on move 81 Stockfish gave the bishop for one of the white passers. The game was adjudicated on move 99 when Leela lowered its eval for the draw rule.
In game 84 the engines started similarly, with a pawn exchange in the center and a knight exchange, though with slightly different moves. Evals were mostly stable, the engines shuffled for a while. Stockfish pushed pawns on the king side, on move 32 Leela gave a pawn to open the center. The d file opened and the black queen moved forward. Leela regained the pawn, Stockfish's eval started to increase. In a long PV agreement there was a series of exchanges that reduced to a RR vs RB position with black a pawn up.
Stockfish was down to increments and Leela's eval was low, it was not clear whether Stockfish's eval was real but it kept increasing. Leela created a passer on the queen side, Stockfish moved its rooks forward and captured the passer. Leela seemed to have a fortress on the king side, with the king and rook protecting the f7 pawn and the bishop on the long diagonal holding back the white king and pawns. For a very long time Stockfish moved its king and rooks to limit the black bishop. For a while Leela's eval dropped close to 0, then came back up but was still low. On move 74 Stockfish finally managed to force the black bishop away from the long diagonal. It saw the win in its PV.
Stockfish made sure the bishop stays away, on move 85 it pushed the f pawn and exchanged pawns. Then it pushed the g pawn and the black king became trapped. The game ended in a tablebase win. Stockfish wins the game pair, it leads 29-16.
Games 85-86 started with an 18-ply rare sideline in the English opening. There was one pawn exchange and all pieces were on the board, white had more space and the white king was still uncastled. In game 85 Leela exchanged minor pieces and castled its king. Leela managed to get a protected bishop to c6, evals increased slowly. On move 22 a pawn exchange on the king side weakened the black king support, a minor piece trade got the white bishop to e6 with check. The white queen attacked and Stockfish exchanged queens.
Stockfish exchanged bishops, creating a white advanced passer on e6. The black king moved to the center and captured the passer. A pawn exchange on the queen side created a black passer on the queen side, Stockfish gave a rook for a knight and reduced to a RR vs RN position on move 41.
Leela moved a rook forward and the engines traded pawns. The second white rook moved forward and Leela captured two pawns, it had 3 passers and Stockfish had 2. Both engines pushed passers forward slowly, on move 78 one white passer reached the 7th rank. Leela gave a rook and queened the passer, Stockfish had a passer on the 2nd rank while Leela queened a second passer, the game ended in mate.
In game 86 the engines repeated game 85 for 21 plys with transposition, Stockfish castled its king and moved a bishop to c6. Leela pushed pawns on the queen side, trapped the white bishop and created a passer. In a series of exchanges the white c6 bishop was exchanged as well as the queens. The game reached a RRB vs RRB position on move 27, Stockfish had a blocked passer on c7.
Stockfish's eval slowly increased while Leela's eval stayed stable around 1. Leela captured the white passer and Stockfish opened the d file. The engines avoided exchanging rooks, there was another pawn exchange and Leela doubled rooks on the c file. Stockfish blocked the black passer, the white king moved forward and a pair of rooks was exchanged. On move 58 Leela's eval started to slowly increase, the white king kept moving forward until it reached d8, attacking the black bishop.
Leela tried to keep its bishop, it exchanged rooks and gave pawns to save it. The game reached an opposite color bishop ending, Stockfish had a passer on the queen side and it kept the black king away. Leela captured two pawns on the king side but lost its bishop for the passer, the game ended in a tablebase win. There were two white wins in this pair, Stockfish leads 30-17.
Games 87-88 started with a line in the French Winawer, advance variation played in high level human chess. The center was blocked, all pieces and pawns were on the board and both kings were uncastled. In game 87 Stockfish thought for 42 minutes on its second move, the engines pushed pawns on the queen side, Stockfish exchanged a pair of bishops and the white king moved without castling. The engines locked the queen side, evals slowly increased as Stockfish castled long and the white king walked to the queen side. Stockfish's eval came back down a little, Leela moved its major pieces to the king side, it captured a pawn and exchanged queens and a pair of rooks.
The black king walked back to the king side, Leela moved its knights to the queen side and its eval drifted down. On move 46 Leela pushed the g pawn to open the king side and evals jumped. After a minor piece exchange Leela created a passer on f6, the white rook moved forward and the game reached a RB vs RN position.
Stockfish captured the white passer, Leela captured the black b and d pawns and created two more passers. Stockfish captured the white d pawn and Leela captured the black h pawn. Leela pushed the h passer and Stockfish lost material to stop it, the game ended in mate.
In game 88 Leela made a different choice on its second move, there was a bishop exchange but the white king did not move. There was a pawn exchange on the king side, the queen side stayed active. Leela walked its king to the queen side, the engines exchanged pawns and a pair of knights in the center and evals increased. Leela moved its queen forward on the queen side and Stockfish blocked its retreat. A series of exchanges opened the c file, Stockfish created a passer on the d file and Leela had one on the a file. On move 36 the game reached a QRB vs QRN position.
The white king was under threat but safe enough. Stockfish moved its major pieces forward on the king side and captured 3 pawns. Leela captured one pawn on the queen side but the white passers were much more dangerous than the black ones. Both minor pieces were captured, Stockfish saw the win in its PV. Leela captured a white passer on the 7th rank, there were more exchanges and the game ended in a tablebase win. There were two white wins in this pair, Stockfish leads 31-18.
Games 89-90 started with a 20-ply sideline in the open Ruy Lopez, Bernstein variation. There was one pawn exchange, all pieces were on the board and the black king was still uncastled. In game 89 Stockfish captured a pawn in the center, Leela used a pin to captured a pawn on the queen side. Leela opened the a file, the engines exchanged a pair of rooks and minor pieces. Evals came down, Leela was a pawn up but Stockfish had a bishop pair advantage. The game reached a QNN vs QBB position, in another series of exchanges the engines reduced to a N vs B ending on move 35. Leela's eval was too high for the draw rule, the game continued for 30 moves before adjudication.
In game 90 the engines exchanged pawns on the queen side and a pair of bishops. Stockfish pushed the e pawn and exchanged it, the black king moved without castling. After move 17 Stockfish's eval started to increase while Leela's eval drifted down. Stockfish doubled queen and rook on the a file, a series of exchanges started on move 23 and Leela's eval jumped. The engines exchanged knights and rooks and opened the a and b files.
The white queen moved to the back rank and pinned the bishop. All minor pieces were exchanged and the game reached a QR vs QR position with white a pawn up. Stockfish avoided exchanges and arranged its pawns, its eval increasing quickly while Leela's eval stayed stable. On move 46 the rooks were exchanged.
Stockfish's eval was very high, again it was down to increments. Leela's eval did not increase, Stockfish repeated checks, n move 63 there was a pawn exchange on the king side. Leela chased the white king across the board and Leela's eval started to increase. On move 99 the white king reached e6, Stockfish saw the win in its PV. There were a few pawn trades and the game ended in a tablebase win. Stockfish wins the game pair, it leads 32-18.
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