Faf du Plessis, South Africa's captain, says that his team will have to cobble together a new strategy to stay alive in the World Cup, after a disastrous defeat to Bangladesh at The Oval was compounded by a hamstring strain for Lungi Ngidi that will keep one of their premier strike bowlers out of action for up to ten days.

With Dale Steyn, their iconic attack leader, still inching his way back to fitness following a shoulder problem, du Plessis admitted that "Plan A is gone", having come into the World Cup with hopes of deploying those two men alongside Kagiso Rabada to form one of the most formidable pace attacks in world cricket.

And now, with just three days to dust themselves off before taking on India in their opening World Cup fixture in Southampton on Wednesday, du Plessis said that he was still searching for answers as to why South Africa's campaign has got off to such a poor start.

"I have to believe that we can still win the World Cup," du Plessis said. "I won't be South African if I said no.

"I'll go back and try and see how we can lift the spirits in the team. We're playing a strong team in India in their first game, and our third game, so as a team, we know. We know we're not good enough at the moment and we have to turn it around.

"It's not like international cricket [is] 'there you go, there's a win for you'. The World Cup is set up with strong teams, and we have to win. We have no other choice. We won't be going back and just falling over, I can promise you that."

South Africa's performance was fatally undermined when Ngidi left the field after bowling just four expensive overs in Bangladesh's record ODI total of 330 for 6. He did not reappear, even to bat, and Dr Mohammad Moosajee, the team doctor, confirmed he would be sent for scans after experiencing "sharp discomfort in his left hamstring".

"Look, it didn't go according to plan," said du Plessis. "We spoke a lot before the game about trying to be aggressive, but obviously then Lungi got injured and that changed completely.

"Now all of a sudden, as captain, I have to bowl 15 to 20 overs of medium to slow or spin or bowling, so then you need to bowl the team out in order to make sure that you don't have to chase a big score.

"But the nature of subcontinent teams is that they do get a big score on the board, they can squeeze you when they have runs on the board, and that's exactly what happened."

Options for South Africa are thin on the ground going into the India fixture. Dwaine Pretorius is waiting in the wings as a seam-bowling allrounder, and Tabraiz Shamsi could conceivably link up with Imran Tahir in a twin-spin attack. But their ideal scenario, of fast and hostile bowling to cow their opponents into submission, is now to all intents and purposes over.

Plan A is gone," said du Plessis. "It's gone because Plan A was those bowlers playing together. They haven't played a game together on this tour.

"Initially Plan B was Anrich Nortje, an extra pace bowler that we had lined up for if we had an injury, to have another X-factor bowler that can bowl 145 plus. He got injured, as well.

"So now you're moving into your all-rounder territory. You have two medium pace all-rounders and then you have Chris Morris that like sits in between your fast bowlers and your medium pace bowlers.

"So, now, we have to really look at what we can do to try to be effective; is it playing all-rounders together, do we play two spinners. Now it's reshuffling all our cards and see how best we can deal with it."

Steyn is at least making progress towards his long-awaited return. He practised in the middle after the match, and should be close to consideration for the India game. However, having not played competitively since the IPL in April, and with a possible six must-win matches still to come in the group stages, his realistic return may be deferred until the West Indies match on June 9.

"Any captain would say that it's not easy [managing injuries], but I mean, I can't complain about it," said du Plessis. "That's not going to change anything. I have to find a way. The coaching staff, the team, has to find a way. It's not going for us from an injuries point of view."

For now, du Plessis' task is to motivate a dispirited dressing room, and he warned that - whereas there was comfort to be taken in the manner of their opening defeat against India - the Bangladesh loss was a different matter altogether.

"From my style of captaincy, has always been there's a line, and if you don't perform to that line, then there's a lot of harsh words," he said. "I'm certainly not Mr. Nice Guy. There's times for strictness and there's times that you see a dressing room needs you to be strong and to motivate them, and that was the previous game when we lost to England the way that we did.

"But now, today was not good enough. There's absolutely no excuses from me. So if the guys think they can make excuses for a performance like today, then they will be challenged. That's a fact.

"At the moment, it's a skill thing. Our skill is not where it needs to be. It's got absolutely nothing to do with injuries. You can make excuses, as many as you want. But every single player in our dressing room is not playing to their full potential, and that's why we're not putting the performance on. It's just about making sure you look at yourself in the mirror and see how you can find that answer."