Captain Alastair Cook blamed poor fielding for England's
80-run defeat by South Africa
in the second one-day international in Southampton.
Wicketkeeper Craig Kieswetter dropped Hashim Amla twice during his innings of 150 as the Proteas made 287-5.
England were bowled out for 207 to relinquish top spot in the
to their opponents.
International Cricket Council one-day rankings
"You cannot afford to give good players two or three chances," said Cook.
"Hashim Amla was the backbone of their innings, but we had our chances in the field."
Amla shared an opening stand of 89 with Graeme Smith, who made 52, and partnerships of 65 with AB de Villiers and 55 with Faf du Plessis for the fourth and and fifth wickets respectively.
Ian Bell and Samit Patel made 45 in England's reply, but the loss of regular wickets undermined their pursuit on a slow surface.
"A lot of our players got in but only got 10s, 20s and 30s," added Cook.
"We did not have that 130-140 run partnership which you need when you are chasing 288. We spoke about it but we did not deliver it today."
Defeat saw England drop to third behind India in the ICC rankings, although they can reclaim top spot if they win the third game of the five-match series at the Oval on Friday.
Top of the ODI rankings
South Africa - 124 points
India - 120
England - 118
Australia - 112
Sri Lanka - 108
Pakistan - 105
Cook insists he is focused on winning that match - and the series - rather than regaining the number-one position.
"It is a bit strange to be talking about it game by game," he said.
"We have three more games to play and we are still a good side; one bad performance does not change that.
"We are still in this series and we have to come back and play better than we did today."
South Africa captain AB de Villiers was pleased by his side's display in their first completed ODI since their series victory over New Zealand in March.
"It is the first one-day international after quite a few months without ODIs and I was not expecting us to play that well," he said.
"We did not play the perfect game - we are a long way from that - but I was very impressed with the guys."