Batsman Bhanuka Rajapaksa said Sri Lanka have shaken off their underdogs tag and proved they can challenge at next month's T20 World Cup, after beating India to stand on the verge of the Asia Cup final.

Rajapaksa's side bounced back from a crushing opening defeat against Afghanistan to register three straight wins in the Twenty20 tournament, which was moved from Sri Lanka to the United Arab Emirates because of political unrest and an economic crisis.

Skipper Dasun Shanaka and Rajapaksa put on unbeaten stand of 64 to help Sri Lanka chase down 174 to beat pre-tournament favourites India by six wickets in the Super Four match in Dubai on Tuesday.

"We were underdogs from the time that we came to the UAE. We all know how Pakistan and India are on their day," said Rajapaksa, who hit an unbeaten 25.

"So we had less pressure and all we wanted to was prove a point to the world, especially to our nation because with all the crisis happening back home this is the only thing with which we could bring smile to their faces."

If Pakistan beat Afghanistan later on Wednesday, they will face Sri Lanka in Sunday's final and knock out arch-rivals India in the process.

Sri Lanka, who won the 50-over World Cup in 1996 and the T20 World Cup in 2014, have enjoyed success on the field this year despite the country reeling from fuel and food shortages and rolling blackouts.

"After the statements that we have made, I don't think we could be called underdogs any more," said Rajapaksa.

"I think so far we have done it quite well and we have really good chance of clinching the World Cup."

The team won rich praise for the win over India with former captain Mahela Jayawardene, tweeting: "Great win boys!!! Attitude was brilliant. Never gave up... keep it going."

Rajapaksa added: "No matter what state we come to UAE, the end goal is to win the trophy, we want to clinch the title.

"So I think we are pretty confident as a team. Everyone is clicking."

Another ex-captain, Kumar Sangakkara, lauded the team's "never say die attitude" and "sparkling talent and ability".

Rajapaksa said that keeping faith with a settled squad of Sri Lankan players had helped to build confidence.

"From captain's view, and selectors and coaches, they have been backing the players and it's a very good sign," he said.

"Going forward it will really help Sri Lankan cricket to rebuild their brand, which was there a couple of decades back."