England captain Jos Buttler admitted his decision to bat first in the Mumbai heat was a crucial error after their World Cup hammering by South Africa on Saturday.
The defending champions won the toss and opted to bowl, but laboured in the humid conditions and allowed South Africa to rack up 399 in their 50 overs.
Their reply then folded spectacularly to 68-6 and then 170 all out in 22 overs to record a humiliating 229-run defeat. The returning Ben Stokes was one of those to fail with the bat as he made just five.
Buttler said: "It’s incredibly disappointing, we came here with high hopes to play our best cricket and we were short of that and well beaten.
"Potentially we should have batted first with the heat. You always look back on the decisions you made. It was incredibly tough conditions, we saw that with the boys in the field."
England made a good start, removing South African opener Quinton de Kock with the second ball of the innings, but when tall seamer Reece Topley had to leave the field with an injured finger, the game changed.
"Throughout the first innings lots of things didn't go to plan," Buttler said. "We started nicely and then Reece picked up that injury. We then had the unknown of whether he was going to come back and bowl, so we tried to fiddle a few overs in.
"I thought if we could have restricted them to 340-350, probably on this pitch it would have been a really good chase. They just got away from us at the end."
South African power hitter Heinrich Klaasen did much of the damage with a 67-ball 109. He put on 151 for the sixth wicket with Marco Jansen.
It was a fourth ODI ton for Klaasen, who has emerged as a game-changer in the middle order for South Africa, able to score at a rapid rate and provide impetus in the closing overs of the innings.
"It is up there with my best ever, I have been hitting the ball nicely, but the conditions were brutal out there," said Klaasen. "It is proper heat that saps all the energy out of you.
"Quinny (Quinton de Kock) came upstairs and said, ‘Don’t run your ones too hard, make sure you can walk a quarter of your runs, save energy’.
"The heat was extreme. They (England bowlers) looked like they were physically under the pump."
England have now lost three of their opening four games of the tournament ahead of their next game against Sri Lanka on Thursday.
"It leaves us with no room for error, we probably have to win every game from here on in," Buttler said.