After 90 games Stockfish leads 28-15 with 47 draws. Stockfish won 3 game pairs without loss, increasing its lead to +13 with 5 game pairs left to play. Leela hasn't been able to win a game pair for 16 straight pairs, it is not making a comeback this season. There was on game pair with two white wins.
Games 81-82 started with a line in the QGA, central variation, played in high level human games. All pieces were on the board, black was a pawn up and had a passer in the center. In game 81 there was a long PV agreement at the start, the engines exchanged minor pieces, Leela regained the pawn and attacked the black king. Stockfish moved its exposed king without castling, Leela captured two more pawns and cleared the black king side. There were 4 connected white passers but the white king was behind them. Stockfish captured one passer and Leela's eval dropped. In a series of exchanges the engines reduced to a RB vs RB position. Leela was two pawns up with a passer on the 7th rank, Stockfish also pushed a passer to the 2nd rank. Both evals were close to 0 and the game was adjudicated.
In game 82 Leela kept the pawn and kept its king safe, Stockfish's eval jumped when Leela castled its king and allowed a king and rook fork, losing a rook for a knight. Two moves later Leela's eval jumped even higher. Stockfish opened the c file and moved a rook forward, Leela pushed a pawn on the king side that reached h3 and the white king hid behind it. Stockfish used all its pieces to threaten the black king, Leela exchanged pieces and pawns, on move 44 the game reached a RR vs RB position.
Stockfish created a passer on the queen side, then managed to confine the black king on the h file. A zugzwang on move 62 forced Leela to move its blocking rook, Stockfish used mate threats to push its passer and gain more material. Stockfish queened and the game ended in a tablebase win. Stockfish wins the game pair, it leads 25-14.
Games 83-84 started with a rare sideline in the Robasch defense. In game 83 the engines castled in opposite directions. For one move Leela's eval spiked close to 2 after a 12 minute think, Stockfish surprised with a pawn push on the queen side and both evals dropped. The engines opened files and exchanged pieces rapidly. Stockfish was a pawn up in a QB vs QB position, Leela regained the pawn and exchanged queens, the game was adjudicated very early on move 34.
In game 84 the engines repeated the reverse game for 11 plys and castled in opposite directions. The black queen moved forward on the queen side, the engines exchanged pawns and minor pieces there. Stockfish captured a pawn, most of the black pawns on the queen side were gone and the black pieces there were a threat to the white king. Stockfish exchanged a pair of rooks and protected its pawn on e5 that kept the long diagonal closed. Leela's eval dropped on move 28, Stockfish's eval dropped 2 moves later. The engines exchanged pawns on the king side and opened files but it seemed Leela found a way to hold a draw. On move 38 Stockfish's eval jumped back up, Leela was surprised by the next white move.
The white bishop was hanging but Leela didn't take because of the threat of Qh4, allowing Stockfish to capture back and also threaten the black king. Stockfish had to be careful because Leela had mate threats as well, but Stockfish kept its king safe. Eventually Stockfish gave a bishop for a pawn and then captured the black knight so it was two pawns up. It chased the black king to the queen side and protected against a back rank mate.
Stockfish exchanged queens and captured the remaining black pawns. It was 3 pawns up in a RN vs RB position and the win was just a matter of time. Leela avoided exchanges, Stockfish pushed its passers forward and mated in the end. Stockfish wins the game pair it leads 26-14.
Games 85-86 started with the Old Indian, Tartakover variation, with the white queen out on the queen side. In game 85 Leela pushed a pawn on the king side, Stockfish captured it and opened the g file. The engines exchanged most minor pieces and both castled long. Leela regained the pawn and captured another one, evals slowly increased. Stockfish placed its pieces around the king and waited for the attack, on move 41 the engines exchanged a pair of rooks and the game reached a QRB vs QRN position.
Leela attacked the center and opened the e file. After another pawn trade Leela created a passer on the king side. The engines exchanged queens and Leela pushed its passer. Stockfish lost more material as it created its own passer on the queen side. However Leela queened and the game ended in a tablebase win.
In game 86 the engines repeated the reverse game for 25 plys, exchanging most minor pieces and opening the g file, Leela was up a pawn. Stockfish moved its king to the king side without castling, stabilized its pawns and then reduced to a QRR vs QRR position. Leela castled long and Stockfish captured two pawns on the king side. On move 35 the engines exchanged a pair of rooks, evals were already high.
Stockfish captured a pawn on the queen side while Leela tried to attack from the king side. The black queen moved forward and the engines exchanged rooks. Stockfish saw the win in the queen ending though it was a long endgame. Leela captured a pawn, the white king move forward and captured two pawns in the center. Stockfish pushed passers forward and Leela lost its queen, the game ended in mate. There were two white wins in this game pair, Stockfish leads 27-15.
Games 87-88 started with a 20-ply sideline in the Nimzo-Indian, Saemich variation. The center was blocked with one pair of pawns exchanged and all pieces were on the board. In game 87 the engines played mostly behind their pawn lines, Leela's eval increased for a while and then came back down again. Stockfish exchanged a pair of pawns on the queen side, then blocked it with pawns and pieces. Leela was left without knights after an exchange, Stockfish also exchanged its last knight. Leela doubled rooks on the g file and used mate threats to capture a pawn. Stockfish doubled rooks on the a file and kept its king safe. After some shuffling the engines exchanged a pair of rooks, the game was adjudicated after queens were exchanged.
In game 88 Leela pushed the g pawn early and Stockfish thought that was a mistake. Leela's eval stayed low while Stockfish exchanged a pair of pawns on the king side and doubled pawns on the f file. On move 19 Leela's eval spiked over 3, but Stockfish did not play what Leela expected and its eval dropped back. Then there was a series of exchanges, Leela's eval increased back to around 2 and the game reached a QRB vs QRN position.
Leela was a pawn up and its king seemed reasonably safe, but still evals were high and increasing. Stockfish shuffled and repeated for a long time, the focus was on the f6 pawn. After a while Stockfish managed to get the black king away from the pawn. Leela did not have enough defenders and it lost the pawn, the black king ran to the queen side.
Stockfish gave a pawn in the center and created a passer, then exchanged queens. The passer moved forward, Stockfish gave a rook for a knight and queened the passer. The game ended in mate. Stockfish wins the game pair, it leads 28-15.
Games 89-90 started with a sideline of the French Winawer, advance variation. In game 89 the white queen moved forward on the king side, after a minor piece exchange the black king moved without castling. Leela gave a pawn and opened the b file, Stockfish exchanged a pair of rooks and reduced to a QRN vs QRN position. The engines started to shuffle, with a few pawn moves and pawn exchanges. Stockfish's eval was 0, Leela lowered it eval after a series of exchanges on move 111 that included the rooks, the game was adjudicated a few moves later. In game 90 the engines repeated the reverse for 26 plys with transpositions, the black king moved without castling, Stockfish gave a pawn and the b file was open. Again the engines reduced to a QRN vs QRN position, then started shuffling with a few pawn moves. Evals came slowly down, on move 114 Stockfish gave pawns, the game was adjudicated after a knight for rook trade.
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