There was plenty of action and blood on the board in round 5 of the Gashimov Memorial in Shamkir today. Three of the five games had a winner, and it could have been four. Moreover, all the decisive games involved the leaders, and not always to their advantage.
In fact, the player who was leading the tournament, Wesley So, received his comeuppance today at the hands of Viswanathan Anand. It was their first game against each other, and Anand made sure to seize the psychological advantage for their future battles. In a 6.d3 Ruy Lopez, So repeated the rare move 9...Nb8 he had used against Fabiano Caruana earlier in the year. There he drew, but Anand was ready with a very nasty attacking idea that became clear when he played 14.f4. Objectively, this doesn't offer White an advantage, but practically it posed Black serious problems. As far as I can tell, Black is okay if he plays 16...Nh6, but So played 16...Bg5, admitting in the press conference that he had missed Anand's 17.h3 in reply. After that, So defended well (ignoring an exchange of minor errors on Black's 21st and White's 22nd moves) and might have been able to hold the position that arose almost by force after White's 29th move.
Unfortunately for him, he failed to find the key to the position. His 29...d5? 30.h5 d4? was probably intended to create the possibility of a check for his queen on e3, so that if White's queen strayed a little Black could get some counterplay and perhaps a perpetual. Instead, he should have played ...a5, ...c5 and generally ...a4, trying to keep lines closed for both the queen ending and a possible pawn ending as well. Even if that does lose down the road - and I'm not sure it does - it would have been much harder to break Black's position in that case. After So's errors, Anand was able to break open the center almost immediately and win easily.
That allowed Magnus Carlsen to leapfrog So and take clear first, after his great win over Maxime Vachier-Lagrave. The players left theory pretty early in a Reti/Polish Defense (1.Nf3 Nf6 2.g3 b5), and Carlsen did his thing and outplayed his opponent a bit at a time, one stage at a time. The first stage concluded with 22...Qf6?! 23.Bh5, after which White had a clear and enduring advantage, but nothing close to a win. MVL managed to keep the damage from getting worse through the end of the first time control, and it was only a couple of inaccuracies on moves 42 and 43 that allowed Carlsen to obtain a winning advantage. This took some great play by Carlsen, and he was up to the challenge. The final mating net he constructed with 50.Rxh7, 52.h5, 53.Rh7 and finally 54.Bd5 was especially nice, and Vachier-Lagrave resigned rather than see 54...a1Q 55.Rf7+ Kg5 56.Rf5# on the board.
The third decisive result of the day was Shakhriyar Mamedyarov's win over Vladimir Kramnik, which was apparently his first win (at least in classical chess) over the former champ in his career. Mamedyarov had an enduring initiative in a Semi-Tarrasch, but no advantage for a long time - both players were producing very high-level, error-free chess until move 31. Kramnik needed to play 31...Qxd6 32.Na4 Ra5, when he would maintain equal chances. Instead, 31...axb6 32.Qb3 led to a position where Black could only eliminate White's dangerous d-pawn by entering an ending with a porous kingside with weak pawns on h6 and f6. Later on Kramnik could have put up more resistance, but practically speaking the task was probably almost impossible.
There was almost a fourth win, as Fabiano Caruana came out of the opening with a huge, probably winning advantage against Anish Giri. This is not last year's Caruana, however, and he let Giri slip. It's likely or at least reasonable to think that he had looked forward to the position that arose after his 29th move, which does indeed look overwhelming. It's hard to believe, but there just isn't anything there for White, and after some exchanges the players split the point.
The final game was a dull draw between Rauf Mamedov and Michael Adams. Black was able to liquidate the center in a Yates Variation Ruy, and shortly thereafter almost all the pieces were liquidated as well.
The games, with my notes are here, and with more comments than usual it will hopefully tide you over for tomorrow's rest day. Here are the pairings for round 6, on Thursday: