Luke McShane and Magnus Carlsen are sharing the lead after four rounds at the London Chess Classic. McShane, who beat his compatriot David Howell with Black on Tuesday, even has the tiebreak advantage. Carlsen drew with Vladimir Kramnik. Vishy Anand finished his long streak of draws with a loss against Hikaru Nakamura while Nigel Short got his first three points thanks to a win against Mickey Adams. In this round Levon Aronian had his rest day. There's no round on Wednesday.

Carlsen and McShane lead with five rounds to go | Photos © John Saunders, all other photos in this report © Ray Morris-Hill for the official website

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The fourth round of the London Chess Classic started about 16.15 local time, or 17.15 CET. It was scheduled for two hours later than normal because of a Chess in Schools and Communities junior tournament, which was delayed a bit at the end.

However, for the spectators, and especially those in the USA, it was worth the waiting as they would witness another great round.

Let's start with what the organizers dubbed as the first US player to beat a reigning world champion for 19 years. They probably referred to a tweet by Mig Greengard, who thinks the last time was Kamsky over Kasparov at Dortmund 1992. Hikaru Nakamura beat Vishy Anand in a King's Indian that could easily have swung the other way.

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It's really live or die, and nothing in between, in Nakamura's KIDs! He explained his opening choice like this:

I didn't like the way I lost yesterday. I figured that if I lose at least I should give myself some chances. Vishy has only been playing 1.d4 for the last couple of years and he has very little experience with the King's Indian. I thought he wouldn't understand the structures as well as I did.

To the question whether this was his biggest single win, Nakamura answered

Probably overall it is. I had some better quality wins but certainly beating the World Champion... the first time you do that is something special.

Later that night he tweeted:

Live by the sword and die by the sword. Sometimes I wonder just how many of these games I can play in the KID before I die of a heart attack

Magnus Carlsen got some chances in an ending with opposite-coloured bishops and rooks against Vladimir Kramnik. The Russian wasn't happy at all with how he got out of the opening - the same in which he once beat Garry Kasparov in a blitz game.

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Magnus Carlsen had to be satisfied with a draw against Vladimir Kramnik

This allowed Luke McShane to catch Carlsen in the standings.

With Black he beat David Howell, who suffered a case of chess blindness - in timetrouble he went for a tactical sequence that looked brilliant, until it turned out to be... incorrect.

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During the commentary Levon Aronian said about McShane:

Luke is very gifted positionally, and works really well during the game.

Nigel Short scored his first win in three London Chess Classics against Mickey Adams, thereby also avenging his British Championship tie-break defeat.

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Nigel Short washes away that nasty zero on the leaderboard with 3...h6 in a French...

...a move that prompted the legendary Viktor Korchnoi, here with Julian Hodgson in the VIP room, to say: "Switch the game!"

On Wednesday the players don't have a round. There is chess in Olympia, though, as the FIDE Open and the Women's International reach their fifth round. Besides, there's a Chessbase workshop, a Bobby Fischer Against the World screening and an astronomy lecture by Vishy Anand (!) and John Nunn.

Round 4 standings

Round 4 standings (classical)

London Chess Classic 2011 | Schedule & results