DUNEDIN: Sri Lanka captain Angelo Mathews admitted his side must raise their game if they are to win a second World Cup after surviving a scare against Afghanistan at University Oval in Dunedin on Sunday.

Mahela Jayawardene's 19th one-day century rescued the 1996 champions from a perilous 51 for four in pursuit of a 233-run target after openers Lahiru Thirimanne and Tillakaratne Dilshan both fell for golden ducks.

Jayawardene (100) and Mathews (44) put on a crucial 126 for the fifth wicket to steady the ship before Thisara Perera smashed a quickfire 47 not out to see them home.

It was 1996 champions Sri Lanka's first win of this tournament after an opening 98-run loss to New Zealand, while debutants Afghanistan have now been defeated twice following a first-up 105-run drubbing by Bangladesh.

“We really need to raise our standards to compete against the top teams,” said Mathews, whose side next face Bangladesh on Thursday, with further Pool A fixtures to come against Australia, England and Scotland.

“I am feeling relieved at the moment but I thought we came back well. It was a see-saw kind of game. They started off well and then we pulled it back in the end. I knew I had to stay out there with Mahela to get some kind of stand going.”

Afghanistan captain Mohammad Nabi admitted his team's 232 all out was always going to be hard to defend.

“I felt we were short by 30-40 runs. We bowled really well in the first 10-15 overs, we put pressure on them in the end. We kept them to a tight game, so we are pleased by that,” said Nabi, whose team next play Scotland in Dunedin on Thursday.

Jayawardene, who was named man-of-the-match, praised Afghanistan and said the gap between Test nations and the second tier Associate sides was narrowing all the time.

“All credit to Afghanistan. They batted really well in tough conditions, then followed it up beautifully with the ball,” said the 37-year-old.

“They have pace, movement and they're a handful. There is not a big gap between the top countries and these guys.”