South African skipper AB de Villiers blamed "unforced errors" and "miscommunication in the heat of the battle" for the 26-run loss to India in their Champions Trophy in Cardiff.
De Villiers said losing Morne Morkel in the 34th over of due to a strain in the left leg was also quite a "shock" because he was the lynchpin of his team's seam attack.
Opener Shikhar Dhawan bludgeoned his way to a maiden ODI century as a rejuvenated India kicked off their campaign with a comfortable victory in Cardiff on Thursday.
"But I still feel our boys fought back well to restrict India (to 331)...it could well have been 370," he told reporters in a post-match chat.
Talking about the "unforced errors" and "miscommunication in the heat of the battle", de Villiers recalled the dismissal of key batsmen like Robin Peterson and David Miller to silly run outs. Peterson's exit at the team score of 155 for three proved to be a turning point.
"The run outs proved to be costly but you can't do much about them. When the players are trying to do their best and your heart is pumping, the heat of the battle makes you make errors," De Villiers explained.
"We have to win our next two matches because in a short tournament, there are no margin for errors. We come here to win all games and we will take a lot of positives from the defeat against India," De Villiers said.
But the skipper's plans may take a hit because Dale Steyn is still doubtful for South Africa's next game against Pakistan in Birmingham.
"We will assess the situation every day and then hope for the best, but missing both Steyn and Morkel will be a massive blow," De Villiers said.
Morkel was rushed to a doctor for scans in his left quadriceps. He may take a maximum of seven days to recover, according to the South African team doctor.