London: Angelo Mathews says an inspirational session in the nets with Kumar Sangakkara laid the foundations for Sri Lanka's stunning Champions Trophy victory against India.

Sangakkara is retired from international duty, but the legendary Sri Lanka batsman is currently playing for Surrey and he took the opportunity to spend some time with his country's emerging youngsters before Thursday's crucial clash with India.

Still in fine form with Surrey, Sangakkara opted against coming out of retirement for the Champions Trophy, but the 39-year-old clearly still has an influence off the field.

Sri Lanka were thrashed by South Africa in their opening match last week but bounced back on Sangakkara's temporary home ground, chasing down India's total of 321 to win by seven wickets at The Oval.

It was Sri Lanka's joint highest ODI run chase and kept alive their hopes of reaching the semi-finals.

Danushka Gunathilaka, standing in for the injured Chamara Kapugedera, hit 76 off 72 balls while Kusal Mendis made 89 as the pair set in motion an unlikely victory.

And Sri Lanka captain Mathews revealed some tips from Sangakkara this week helped turn the tide.

"Kusal met Sanga to get some batting tips because he is the king," Mathews said.

"We all look up to him and take advice from him, all the batters. He taught us good things about how to play on these tracks.

"The guys met him, took a lot of advice and went out there and did it today."

Gunathilaka's ODI career-best innings was especially impressive as he would have been watching in the stands if Kapugedera hadn't been ruled out with a knee injury suffered in practice on Wednesday.

Gunathilaka and Mendis put together a 159-run partnership before Mathews (52) and Asela Gunaratne (34) finished the job with eight balls to spare.

In the midst of a major rebuilding project, Sri Lanka will clinch an unexpected place in the last four if they beat Pakistan on Monday.

"For Danushka to walk into a game knowing he wasn't even in the 15 until after Chamara got injured is impressive," Mathews said.

"He had to step in against a very strong opposition and I was very impressed with how he batted.

"He and Kusal played with a lot of freedom and that set us a platform and made it so much easier for myself and the middle order batters.

"Asela's little cameo as well really won us the game at the end so it was a fantastic batting effort."

- No guarantees -

India seemed to be in control after Shikhar Darwan scored 125, while Rohit Sharma and MS Dhoni made 78 and 63 respectively.

But the holders paid the price for not pushing closer to 350 and now find themselves in a scrap to progress from Group B, where all four teams have two points with one match left to play.

"I personally thought we had enough on the board," India captain Virat Kohli said.

"You have to give credit to the opposition as well. We are not invincible. We are playing against a champion side. 

"These are the top eight teams in the world so there are no guarantees.

"We have to consolidate and then explode at the end, that's how we play. We're not a side that always plays explosive cricket for the 50 overs.

"But if a team has that kind of mindset and executes their shots you have to take your hat off and sometimes say, 'well done'."

India must beat South Africa on Sunday to avoid a humiliating exit.

"Every game is a quarter-final now," Kohli said.

"All teams are on two points and you have to win all your games to go through. We are very clear about the situation."