Kolkata, Dec 21 :World chess champion Viswanathan Anand Monday said he was not unduly worried about his temporary lean patch, though he planned to work on his concentration.

"I didn't do well in 2009, but such things can happen. So, I'm not very concerned," said India's first Grand Master.

Anand said he was not at his best this year. "Motivation and concentration-wise I was not at my peak. I have to work on that".

He was in the city to boost performers of the MindChampions Academy floated by NIIT seven years back.

Anand said that he would have to pull up his socks in time for the Corus championship in January.

On his upcoming World Championship match against Veselin Topalov, Anand said his opponent was one of the toughest players in the circuit.

Comparing Topalov and Vladimir Kramnik, whom he had conquered to lift the World Championship crown, Anand said: "Kramnik will be rated as one of the all-time greats. He plays classical chess, while Topalov's forte lies in his innovation and penetration."(IANS)