Shikhar Dhawan smashed a career-best 137 as defending champions India made 307 for seven against South Africa in front of 80,000 fans in a Melbourne Cricket Ground World Cup blockbuster as Sri Lanka survived a scare against Afghanistan.
Left-handed Dhawan, 29, hit 16 boundaries and two sixes in his seventh one-day international century in a performance which will give India particular heart as they have never lost when the opener has previously hit a ton.
Ajinkya Rahane made 79 while Virat Kohli added 46 to his 107 in India's opening win over Pakistan.
South Africa spearhead Dale Steyn finished with unflattering figures of one for 55 from 10 overs while the Proteas were further hit as seamer Vernon Philander hobbled off the field with a hamstring injury.
Dhawan, who made 73 during the 76-run win over Pakistan in Adelaide last Sunday, put on 127 for the second wicket with Kohli and 125 for the third with Rahane.
Dhawan eventually fell in the 44th over when Hashim Amla, who had floored a difficult chance off Wayne Parnell when the batsman was on 53, picked up an easy catch at fine-leg off the same bowler.  
Kohli and Dhawan came together in the third over after non-striker Rohit Sharma was run out for nought by a direct throw by South Africa captain AB de Villiers from mid-off.
With both teams having won their opening games, the winner will almost certainly be assured of a place in the quarter-finals.
"The wicket was really good and Shikhar was batting really well," said Rahane. "It's a challenging total and the first 10 overs will be crucial for us."
Mahela Jayawardene's 19th ODI century rescued 1996 champions Sri Lanka from a batting meltdown as they beat Afghanistan by four wickets in Dunedin.
Set a modest target of 233 to win the Pool A game, Sri Lanka were stunned when openers Lahiru Thirimanne and Tillakaratne Dilshan both fell for golden ducks.
But 37-year-old Jayawardene (100) and skipper Angelo Mathews (44) steadied the ship with a 126-run partnership before Sri Lanka won with 10 balls to spare at University Oval.
It was Sri Lanka's first win in two games following a 98-run defeat by New Zealand.
"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.
Asghar Stanikzai (54) top-scored for Afghanistan but Sri Lanka were in trouble when they batted with Dawlat Zadran having Thirimanne leg before wicket with the first ball, while Dilshan was caught behind off the first ball he faced from Shapoor Zadran in the second over.
Hamid Hassan then bowled Kumar Sangakkara for seven and Dimuth Karunaratne was caught behind for 23 as Sri Lanka slipped to 51 for four against an Afghanistan side beaten in their tournament opener by Bangladesh.
Hassan came back to end Jayawardene's stand and finished with figures of three for 45.
Sri Lanka were 178 for six, still requiring 54 runs in under nine overs, when Thisara Perera eased their nerves with a decisive and quickfire unbeaten 47.
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 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.
Source: AFP