The 25-year-old middle-order batsman shone with his power shots on debut as a teenager in 2000 and then overcame criticism of his attitude to mature into a dependable player and superb fielder in the last two years.
The Punjab player tore left knee ligaments in October to leave his team concerned for the World Cup but stroked a series-winning 95 not out at home against Sri Lanka last month to display his form and fitness.
"I've worked really hard on my fitness," Yuvraj told reporters on Wednesday. "It wasn't easy coming back from such an injury but you have to build on it.
"I'm sure by the time I play my first game on 17th, I'll be 100 percent."
"That innings (95 not out) was very important for me to build up for the World Cup because I was out for four months and had no runs behind me."
Yuvraj, an outstanding fielder at point, grabbed four wickets bowling his slow left-arm spin in the 182-run victory over unfancied Netherlands on Tuesday.
Skipper Rahul Dravid praised the youngster as key to the team's search for an effective fifth bowler. However, the main focus on Yuvraj - with 4,412 runs from 163 one-dayers - will be his batting.
He has scored fifty or more 33 times, including seven hundreds and India have lost only eight of those matches.
"I've had a good run in the one-dayers in the last two years," he said. "Whenever I go in to bat, I think I need to play till the end, finish the game off.
"The captain has faith in me and that is what I'm going to try and do in this World Cup."
"I'm very happy my contributions have ended up in the team winning, I'll be the happiest to contribute to the team's victory every time but it is not possible all the time."However, Yuvraj felt it would not be easy for batsmen.
"The ball doesn't come on to the bat so you have to spend time in the middle, assess the wicket, opposition and what score you need to put on the board."
He is expected to team up as a part-time spin bowlers with Sachin Tendulkar and Virender Sehwag. "That is an advantage in my team, it is easy to find a fifth bowler," said Yuvraj, rating highly the title hopes. "We play well in such wickets in India also," he said. "But it is going to be do-or-die for every team."
India face Group B opponents Bangladesh in their first match on March 17 in Port-of-Spain, Trinidad. Sri Lanka and Bermuda are the other teams in the group.