LONDON - Sri Lanka lost skipper Angelo Mathews before the toss to a calf injury, and now a must-win clash against India without stand-in captain Upal Tharanga after the opener was banned for two ODIs for a "serious" over rate offence.

Having won the toss and opted to bowl first, Tharanaga's charges too more than four hours to bowl their 50 overs against South Africa in their Group B clash at The Oval on Saturday.  The bowling effort was labelled "ridiculous" by former New Zealand skipper and international coach Stephen Fleming and threatens to further derail the Sri Lankans' tournament following their 96-run defeat by the Proteas.

The Sri Lankas were ruled to be four overs short of their target after time allowances were taken into consideration. When the three and a half hour timeslot to bowl in expired, Sri Lanka were midway through their 44th over. The Sri Lankans eventually completed their overs 37 minutes late with a Hashim Amla century powering South Africa to 6-299.

Under the governing body’s Code of Conduct for the tournament, the sanctions for a serious breach – which is where a side is deemed more than two overs short of the over rate – are hefty, and costly. Under the Code, Sri Lanka's players were fined 60 per cent of their match fee for being over time. ICC sanctions stipulate players lose 10 per cent of their match fee for each of the first two overs, then a further 20 per cent of their match fee for each additional over they are behind time.

For the captain, the penalty is two suspension points, which equates to two ODIs. It rules Tharanga out of Sri Lanka's matches against India at The Oval next Thursday, and Pakistan on June 12 in Cardiff, but he could return for the semi-finals should the team qualify. Underlining the blow this represents for Sri Lanka, Tharanga was the country's best batsman and the only one to reach a half-century against South Africa.

Tharanga hit 57 off 69 balls, with six boundaries, before he holed out to David Miller and became one of Imran Tahir's four wickets for the match. On-field umpires Aleem Dar and Ian Gould reported Tharanaga and match referee David Boon, the former Australia top-order batsman, imposed the sanction. Tharanga pleaded guilty, so there was no formal hearing.

South Africa captain AB de Villiers was hit for a minor over rate offence in the pre-tournament bilateral series against England, but that strike against his name does not carry into the ICC event. Regardless, de Villiers was forthright about his responsibilities with over rates on match eve.

"We've pinpointed areas where we can get better at," de Villiers said. "We just learned the first 10 to 15 overs, where not a lot of fielding changes happen, so there's no excuse to get behind the red in the first 10 to 15 overs. Of course, the game is pretty slow then, anyway. So we've targeted that as an area where we can make up time, get four, five minutes ahead of time, which it does get a bit complicated at the end when there's a partnership going. It's no excuse and it's something we will get right in this tournament. It's just non-negotiable."