London: Virat Kohli hailed India's intensity as the key to their eight-wicket demolition of South Africa as the holders stormed into the Champions Trophy semi-finals.

Kohli's side had to win their final Group B fixture at The Oval to avoid an embarrassing exit and they rose to the challenge with a ruthless display.

The India captain claimed it was their best performance in this year's tournament and he felt their steely focus was the difference between the teams.

"We wanted to step up that intensity. This is probably our best game so far," Kohli said.

"When the opportunity comes your way, you have to grab it. 

"It was a good toss to win. The fielders backed our bowlers."

Shikhar Dhawan's 78 and Kohli's 76 were the key contributions as India chased down 192 with 12 overs to spare.

Kohli saluted Dhawan's composed knock and pin-pointed the needless run-out of South Africa captain AB De Villiers as another crucial moment.

"It's always good to get him out early, he can hurt you," Kohli said of De Villiers.

"It was a decent wicket to bat on. It was important for someone to bat until the end. Shikhar's intent was outstanding."

India will face Group A runners-up Bangladesh in the semi-finals in Birmingham on Thursday as they aim to make the final for the fourth time.

Having thrashed arch rivals Pakistan at Edgbaston in their first match, Kohli expects India to deliver another dominant display.

"We played in Birmingham before. We like that pitch. It suits our game," he said.

"There's no looking back. There's always room for improvement. We can't rest on your laurels."

South Africa's second successive defeat condemned them to a limp exit as they fell well short of winning the tournament for the first time since 1998.

De Villiers' side, who face England in Test and one-day action later this summer, were never in contention against India and the skipper conceded they could have no complaints abut the result.

"It's not an ideal way to finish. Credit to them in those first 15-20 overs, they put the pressure on us," De Villiers said.

"We normally don't bat that way. We never got going. It's very sad obviously. 

"We were hoping to play better but we came unstuck against a better team.

"We couldn't it get away. There were a lot of soft dismissals."