Topalov's Cluster' gave Anand anxious moments

World champion Viswanathan Anand conceded that he and his team of seconds were nervous after challenger Veselin Topalov spent a fortune to secure a super computer with lightning speed ahead of the World Championship match in Sophia, Bulgaria.

The Indian ace won the final game of the 12-game clash in 56 moves to emerge triumphant 6.5 - 5.5 and retain the title he won in 2008.

Topalov obtained the computer 'Cluster', which ran the latest Rybka program, but that was not enough as Anand successfully defended his title.

Anand's preparation, on the other hand, relied more on what he described a "human cluster", with world number one Magnus Carlsen and former World champions Garry Kasparov and Vladimir Kramnik providing generous inputs.

Despite that, Anand conceded he and his team of seconds were nervous after hearing about Topalov's new acquisition.

"We actually started to get a bit worried when we heard about it," Anand said in an interview on Playchess.com.

"So we had to do something in a hurry… Then the people from Hiarcs (a computer chess program) got in touch… That improved matters quite a bit," Anand said.

According to him, computers are useful but it has its limitations too.

"It must be good for the player to have good hardware. The problem is that it often doesn't tell you what you want. You want it to find an improvement for White, and it may choose to find it for Black instead.

"It is also insidious -- it can stop you playing your favourite lines because of some obscure problems somewhere. I would say computers are very useful – especially very powerful hardware – but if working with the computer means you stop taking risks it's of course going to kill you," Anand said.

In that respect, human analysis has an edge, he said.

"With humans it is fantastic, because some of the things they tell you, you can almost relate to. You can almost see how it is something you can apply at the board. In the last few days some of the suggestions came from Vlady (Kramnik) -- very intelligent suggestions, with his explanation of why you should do this or that.

"Or sometimes Garry (Kasparov) will tell you a story about the player, and it is some insight which at a critical moment it may help you to choose between two moves and that can be decisive. So it is a very, very different kind of help.

"Of course these are some of the greatest players in chess, so you can't really ask for more," said Anand.