Kemp, 19, claimed two wickets with her left-arm seam across the three matches of last week's T20I leg of the multi-format series, and bowled her full allocation of overs in their emphatic nine-wicket win in Centurion on Saturday.

Kemp has suffered two stress fractures of her back in recent years, the first of which prevented her from bowling competitively for 14 months, but Knight insisted her withdrawal from the ODI and Test squads in South Africa was due to a surfeit of caution, rather than a recurrence of the injury.

"It wasn't originally part of the plan," Knight said on the eve of the first ODI in Kimberley. "We were hoping to have her available for all three formats but, obviously, with her history with back injuries, she's someone that we have to manage quite tightly and really look after.

"We're gutted to lose her," Knight added. "She's a great person to have around the group, and obviously a hugely exciting prospect for us. But the right thing for Freya was to go home and have a little look at how her back's going, and then hopefully build towards those Ashes.

"We're really hopeful that she's going to be fit and available, but it's a tricky one with stress fractures. You just have to be a little bit careful around loads. She was obviously able to partake in all three games, so that's a good sign, but the decision was made that she wasn't going to be in a place to be ready for the one-dayers and the Test."

England's 3-0 win in the T20Is means they will guarantee themselves at least a share of the multi-format series if they can win the first ODI at Kimberley on Wednesday, with two further 50-over matches to follow in Durban and Potchefstroom, and the one-off Test beginning in Bloemfontein on December 15.

With the Ashes looming in January, Tammy Beaumont and Kate Cross - England's longer-format specialists - are back in contention, as Knight's team seeks to finetune their 50-over plans after successful summer series against Pakistan and New Zealand. A used track is in prospect at the Diamond Oval, which is expected to offer less pace than was on offer in the final two T20Is.

"We haven't played a huge amount of ODI cricket recently, so it's a format that I really enjoy playing," Knight said. "Everyone's pretty excited to get into the longer format, and have a little bit more time to execute your skills and build plans around one day game."

"Obviously with the Ashes, we're not looking too far ahead," she added. "Continuing to have success on this tour is, naturally, going to be the way that we're going to build into the Ashes. The focus very much on South Africa and what they're going to bring against us tomorrow."