The Week in Chess

Magnus Carlsen has taken the lead in the FIDE World Chess Championship by beating his challenger Ian Nepomniachtchi in a record breaking 136 move victory. Both players had winning chances in time trouble on the run up to move 40 but after that it was a master class from Carlsen on how to make the most of your chances. Carlsen deliberately extended the game to put maximum pressure on his opponent when he truly went for victory. Nepomniachtchi played well for long periods but mistakes on moves 31, 36, 38 and a particularly careless one on move 52 contributed to this loss. Nepomniachtchi's fatal error came as late as move 130 by that stage his task was extremely hard - especially with the fatigue that must have set - and if he hadn't blundered at that moment he still had a some way to go to establish a draw.

Carlsen with the white pieces switched openings to a Catalan with a delayed c4 and Nepomniachtchi handled the problems set brilliantly - Carlsen admitted he couldn't remember his prep after the excellent 11...b5 and black had at least equality.

By move 30 Carlsen was down to about six and a half minutes to reach move 40, Nepomniachtchi around twenty seven and a half. Carlsen used more on his next move (down to 3 minutes 5 seconds). Then Nepomniachtchi started using his time - pretty soon both players were in bad time trouble in a very difficult position. Added to which both players had definite ambitions to try and win which led them to take combative decisions.

31...Bb2? from Nepomniachtchi was definitely an error, but its refutation was hard to see and really not in Carlsen's "go to" style - 33.Rd1 turned a "winning" position into one that's probably losing - Carlsen never considered 33.Rcc2 with the idea of sacrificing the entire queen side for a decisive attack on black's king - and in the press conference looked unconvinced when he was asked about it, the other alternative 33.Rxb2 would almost certainly have led to a draw. 33.Rd1? overlooking 34...Qd7 left Carlsen in bad shape but 36...Qd5? (36..Bxb4! and Nepomniachtchi might easily have been the player to go on to win) led to equality again, 38....e4? was a bad error that gave Carlsen a winning position but 40.Nxe4 should have allowed Nepomniachtchi to hold.

52.Kh2 from Carlsen allowed Qe4 threatening Qxh4 but it turned out 52...Qe4 was an error. This was perhaps a final trap from Carlsen in a position that looked likely to finish in a quick draw. After 53.Rxa3 the game entered its longest and eventually decisive phase. Although computers had the position near equal it was Carlsen who was setting the problems throughout and he did this very slowly with the idea that extending the game would be the approach most likely to end in a win for him. His 80.Rxf7+ transforming the material balance yet again was very smart and led to a position where he could torture Nepomniachtchi forever. After move 115 Qxh4 the game entered positions in table bases - that is where the exact proper result of every position is known. Move 130...Qe6? was the decisive mistake (130...Qb1 or 130...Qc2 are drawn with best play) and indeed Carlsen didn't have any problem at all demonstrating he was indeed winning forcing resignation on move 136 after 7 hours and 44 minutes of play.

With games both on Saturday and Sunday Nepomniachtchi will have to be careful he doesn't go on tilt and lose all his chances in a few days.

On 18th July 1978 Korchnoi-Karpov started game 5 which ended in a draw in 124 moves, this was the previous longest game in World Championship history in terms of moves and may still have the record in terms of time it took (there may have been other games longer in time I don't know of). The last decisive game outside of tie-breaks in a World Championship match took place on 24th November 2016 which was Game 10 of that title match where Carlsen beat Sergey Karjakin. In the intervening match all 12 of the standard time control games between Fabiano Caruana and Carlsen in 2018 were drawn.

Game 7 Saturday 12:30 GMT Nepomniachtchi-Carlsen