Shahid Afridi wasn't an entirely happy man after orchestrating "a very big win" over Sri Lanka at the R Premadasa, a result likely to have significant repercussions on Group A as the tournament progresses.

Afridi was at the centre of the triumph, picking up four key wickets as Pakistan overcame a late implosion in the field to sneak out with an 11-run win. The haul included his 300th ODI wicket, the third Pakistani to do so and only the second player after Sanath Jayasuriya to complete 300 wickets and 4000 runs in the format. With nine wickets in two games, he is for now the leading wicket-taker in the tournament.

But Pakistan's inability to finish off games over the last year has worried coach Waqar Younis and tonight's performance, deservedly triumphant ultimately, would not have eased those concerns. Sri Lanka lost their top order with less than 100 on the board, so by the 22nd over of the chase, the game seemed done.

Pakistan relaxed and proceeded to spill three catches, fluff two stumpings and miss a host of run-out attempts over the next 20 overs, allowing Chamara Silva, Kumar Sangakkara and Angelo Mathews to fight back. Amid the bedlam, they swiftly wasted two referrals and totted up 29 extras and though Afridi felt that "80%" of the task was done by then, he warned that improvement was needed.

"It's a very big win for us, beating Sri Lanka before a capacity crowd, their own people and a strong team which has been playing very well recently," Afridi said. "I think when we go ahead in this tournament our destination will get tougher and tougher and if we commit the same mistakes, then we will return to Pakistan very soon. We must improve. Our fielding has been improving since the New Zealand tour, but I don't know why in this match we dropped catches and failed to take run-out chances."

The win was built on the back of contributions from older players; fifties from Misbah-ul-Haq and Younis Khan set up the total and two wickets from Shoaib Akhtar, as well as Afridi's haul, helped defend it. Given the blend of youth and experience in the squad, it was an important contribution. "I'm happy that seniors have taken responsibility," he said. "Younis and Misbah are the backbone of the team, and it's important that the captain performs well as it sets an example for others."

Pakistan have a couple of days off now before their next game against Canada on March 3, also at the R Premadasa. There are likely to be changes for that game, to rest some players, but also for strategic reasons. Pakistan took an unchanged line-up into today's game, which meant they were using just three specialist bowlers and again not fully exploiting Abdul Razzaq: he faced four balls at the death and bowled five tidy overs. Another specialist bowler is likely to be considered. Misbah also picked up a hamstring strain during his innings and though it is not thought to be serious just yet, it might impact on the line-up for the Canada game.

"I will sit down and plan, I will take advice from my coach and from my senior players as it is everyone's team," Afridi said. "Winning is very important for us, it is a good habit and we should try to win every match and play hard with our strength. I think we will give rest to some of our players but definitely we want to win each and every game."