Sri Lanka spinner Maheesh Theekshana on Thursday said defending champions England "underestimated" his team in their key  World Cup clash.

The island nation bundled out a struggling England for 156 inside 34 overs and reached their target with 146 balls to spare in Bengaluru.

Jos Buttler's England slipped to their fourth defeat in five matches to be on the brink of elimination while Sri Lanka kept their hopes alive of reaching the semi-finals.

"I think they underestimated our team because we also lost three games and we only won against Netherlands. I think they underestimated us," Theekshana told reporters.

"That's why the result went our way because we backed our strength, we went with a simple plan, so that's why we won the game today."

Theekshana, who returned miserly figures of 1-21 with his mystery spin, added: "Our confidence as a team has increased a lot because we have won two matches so far. And this match is a match in which we got a very happy victory.

"As a team, we are looking to play well in the upcoming four matches and reach the semifinals."

Fast bowler Lahiru Kumara stood out with figures of 3-35 before Pathum Nissanka (77) and Sadeera Samarawickrama (65) steered the team home in an unbeaten stand of 137.

But it was the return of former captain Angelo Mathews that spurred the team on in the must-win match.

Mathews, who came in as a replacement for injured Matheesha Pathirana, made an instant impact with the first wicket of Dawid Malan, for 38, and later dismissed Moeen Ali, for 15.

Mathews, who has played 106 Tests and 222 ODIs for Sri Lanka since 2008, gave away just 14 runs in his five overs, which included a maiden as well, of medium-pace bowling.

"As a team, we are very happy that a very experienced player has joined our team. He has played in India. We have a lot to learn from him," Theekshana said of the veteran all-rounder.

"Even when we bowled, we used his experience in the match. The whole team is very happy to have such an experienced player on the team."

Sri Lanka, who won the World Cup in 1996, have jumped to fifth in the 10-team table after their second win in five matches.