Baden-Baden (Germany): Former world champion Viswanathan Anand continued to struggle against nemesis Magnus Carlsen of Norway and lost after a blunder in the fourth round of Grenke Chess Classic now underway here.

The loss with white pieces proved quite costly for Anand as he slipped to joint sixth in the standings in the eight-player round robin tournament. The Indian will now be under pressure to score in the remaining three games to come back to a par score.

Riding high on his success against Carlsen in round three, Germany’s Arkadij Naiditsch emerged as the sole leader beating compatriot David Baramidze. Anand and Armenia’s Levon Aronian are joint sixth on 1.5 points each.

Around three weeks ago, Carlsen played the Dutch defense as black and lost to Anand’s long-time second Radoslav Wojtazek of Poland in the Tata Steel tourney. While that was the Leningrad variation, the world champion decided to try out the Stonewall set-up this time to ensure a lively game.

Anand got a slight advantage in the early stages of the middle game that had a typically locked centre but Carlsen made his bid on the queen side by advancing his pawn to the sixth rank. After a rather innocuous plan, Carlsen got the chance to open up the centre and soon his pawn on sixth rank started calling the shots. Anand was not out of the game, but the pressure proved disastrous for the Indian when, on the 32nd move, he simply blundered and walked in to a lost position. The game lasted 36 moves