Leonard Barden chess
3170: Marie Sebag v Ivan Popov, Aeroflot Moscow 2008. How did the Frenchwoman (White, to play) beat the Russian grandmaster? Photograph: Graphic

Magnus Carlsen recovered from a terrible start of two defeats in three games, escaped miraculously from a lost endgame, triumphed at this week’s London Classic, won the €50,000 first prize and regained the world No1 ranking. Yet arguably the 20-year-old Norwegian’s play continued the form crisis which surfaced in October at the world team Olympiad.

The problem is that Carlsen is a different player according to whether he has White or Black. With the white pieces he is sovereign and supreme, exploiting strategic advantages with the subtlety of Anatoly Karpov in his pomp, or patiently grinding and probing in level positions until his opponent cracks in time pressure.

But as Black Carlsen simply tries too hard. Sometimes this impatience becomes manifest when he plays too actively in a level position, as against the world champion, Vishy Anand, in London. And sometimes it shows in his choice of offbeat openings, as in his notorious 1 e4 g6 2 d4 Nf6?! 3 e5 Nh5?! against Michael Adams in the Olympiad. In the game below he also produced a strange knight regroup Nd7-e5-d7-c5 which conceded the initiative to Luke McShane. The Englishman exploited his edge in style.McShane’s own knight forays 18 Nc6! and 22 Na6! looked eccentric but were sharply and accurately calculated.

Luke McShane had the result of his life, justifying his decision to turn his back on a City career and become a full-time chess pro. He would have tied first with Carlsen and Anand on 4.5/7 under traditional scoring (1 point win, 0.5 draw) but the 3/1 system used in London favoured Carlsen. At age 26 and advancing fast up the world rankings, McShane has a chance to reach the elite.

Final scores (3 points per win) were Carlsen 13, McShane and Anand 11, Hikaru Nakamura and Vlad Kramnik 10, Adams 8, David Howell 4, Nigel Short 2.

Overall the Classic proved a fine shop window for top chess. Near sell-out crowds came every day to Olympia to watch the grandmasters play the legendary Viktor Korchnoi in simultaneous matches, listen to commentators including Garry Kasparov, compete in side events or simply relax with social games.

L McShane v M Carlsen

1 c4 c5 2 g3 g6 3 Bg2 Bg7 4 Nc3 Nc6 5 Nf3 d6 6 0-0 Nh6 7 d4 cxd4 8 Bxh6 Bxh6 9 Nxd4 Ne5?! 10 Qb3 0-0 11 Rfd1 Nd7 12 Qa3 a5 13 b4 Ra6 14 b5 Ra6 15 e3 a4 16 Rab1 Bg7 17 Ne4 Qb6 18 Nc6! Re8 19 Nb4 f5 20 Nc3 Qc5?! 21 Nxa4 Qa7 22 Na6! bxa6 23 b6 Nxb6 24 Rxb6 Rb8 25 c5 Be6 26 Rdb1 dxc5 27 Rb7 Rxb7 28 Rxb7 Qa8 29 Nxc5 Qc8 30 Qxa6 Bf7 31 Bc6 Rd8 32 Nd7 Rxd7 33 Bxd7 Qc1+ 34 Qf1 Qxf1+ 35 Kxf1 Bc4+ 36 Kg1 Bxa2 37 Ba4! e5 38 f3! Bh6 39 Bb3+ 1-0

3170 1 Rg6+ Kf5 ( if Kh5 2 Rxe6+ wins) 2 Kf3! Rxe8 3 Rg7! and 4 g4 mate.