World champion Magnus Carlsen missed several chances to win with black in the first game of his title defence, currently continuing in London.
A black win right at the start is by no means ultimately a match winner, but is rather like breaking serve in the first set of the Wimbledon final.
Alexander Alekhine, in 1927 against José Capablanca and again Vassily Smyslov in 1957 against Mikhail Botvinnik, both went on to seize the supreme title after black wins in game one.
In this case, Carlsen built up a dominating position after some highly original opening strategy and an inspired temporary pawn sacrifice and now came the time to reap the harvest.
Caruana-Carlsen: World Championship, London (Game 1) 2018; Sicilian Defence
(see diagram 1)
Here Carlsen played 34 ... h5 but 34 ... Qe5, with the intention of invading on the queenside dark squares, would have led to a winning position as White has no way to organise his defences, e.g. 35 Qh1 Qc3 36 Rc1 Rg3 37 Nf3 b5! and ... c4 will follow ripping White apart on the queenside.
(see diagram 2)
Carlsen now played 38 ... Be5. Instead he should have capitalised on the advance of the h-pawn to h4, which enables the thrust 38 ... Rg3. After 39 Nxg3 hxg3 40 Re2 Qa1 the white queen and rook are hemmed in by the pawn duo on f4 and g3 and his queenside will collapse.
(see diagram 3)
Carlsen now played 39 ... Qg7, missing his last chance to maintain a serious advantage. He should play 39 ... b5, planning ... b4 softening up the queenside dark squares after which Black will quickly obtain a decisive attack. White is unable to defend against this plan.