India will take on the islanders in the first of a three-match series from tomorrow and Dhoni said a lot would depend on how Sehwag performs.
"Of course Sehwag is a great batsman. He is the one who will open the account for us. The way he bats, if he can bat for one or one and a half session, more often than not he crosses the century mark," Dhoni said about the dashing right-hander, who is returning to the side after recovering from a hamstring injury.
"It will be great to have him going. We have Gautam Gambhir and other batsmen who have the potential to score big. Of course, start is important for us. But there is no pressure on Sehwag," he told a pre-match press conference.
Dhoni said ever since the Twenty20 World debacle, the Indian team has been working hard on aspects like fitness.
"It is quite difficult to change all of a sudden. Every player has made a conscious attempt to change a bit of everything. Everyone has put in a bit of effort in training because that is important," he said.
"We are trying to reduce the amount of things that we have and we are having what is really good for us. It has been working," he added.
Asked about India's chances in the match, Dhoni said Sri Lanka start favourites because of the home advantage.
"We will try our best. We have to give in more than 100 per cent in the series because the conditions are more in favour of Sri Lankan team. They know the home conditions better than us," he explained.
"At the same time, it will be a good exposure for the youngsters who are a part of the side. It will just add to their exposure and their experience. Overall, it would be good for Indian cricket in the long run," he added.
Dhoni hoped that off-colour pacer Ishant Sharma would come good in the series.
"Ishant Sharma and Mithun (Abhimanyu) are bowling well. If you are a good Test match bowler, you have to vary your length. I think Ishant has come back in the past when he has played in India or Australia. A lot depends on the kind of wickets you are getting and what time of the day you are good," he said.
On the Lankan spin wizard Muttiah Muralitharan who would retire after the match, Dhoni said he only has fond memories of playing against him in national colours and playing with him in the Indian Premier League.
"I started cricket quite late. But off the field I can say Murali is good to have in the dressing room. He is a great guy. I think there are more memories off the field than on the field because I really don't talk much on the field.
"We have played quite a few series against each other. Of late we have been playing virtually every year against Sri Lanka," he said.