England will decide between Jofra Archer, Mark Wood and Chris Woakes the final spot in their team to face South Africa in the third test, which starts on Thursday.
One of the rhythm players will replace James Anderson, who was injured during the second test win in Cape Town.
"The good thing is that we have three very skilled guys," Captain Joe Root told BBC Sport.
"They will do everything possible to make sure they are ready to leave."
The series of four tests is at level 1-1.
Anderson, England's biggest Test winner ever, suffered a rib injury that knocked him out of the rest of the series.
Archer played in the first test but missed the second with an elbow problem.
Like Archer, Wood offers extreme rhythm as well as reverse swing, but has not played for England since the World Cup final in July after knee surgery.
Woakes last played in the second test against New Zealand in December. Along with Archer and Wood, he was struck by the illness that struck the England national team before and during his first defeat at the Centurion Park test.
"Everyone is coming back from injuries or illness," Root added. "It's really important that we give them the opportunity to make sure we really know where we are.
"The guys have faced the training days they have had so far."
The victory in the second test was England's first in Cape Town since 1957 and was achieved with five players aged 24 and under. All five – Dom Sibley, Zak Crawley, Ollie Pope, Sam Curran and Dom Bess – are scheduled to play at Port Elizabeth.
"Your best win is next, but it was very nice," Root said of his success in Cape Town.
"It was a huge moment for us to level up. It gives us nothing to get into this game beyond momentum and we have to make sure we continue.
"From a young team, it's really important that we don't live this victory for the rest of the tour. We have to try to get over it."
Wicketkeeper Jos Buttler was fined after the second test after trunk microphones caught him cursing at Vernon Philander of South Africa.
"Jos has accepted his rebuke and apologized. He knows that's not the kind of language you want to use in the cricket pitch," Root said.
"You don't want to end this stingy, that competitive element that brings out the best of players on the pitch. Getting the right balance, using the right language, but being competitive is still a good thing. You don't want to completely sanitize the game, but we know our responsibilities.
"In a way, you would like him to choose your words more carefully, but as captain shows how much that means to him."
England's victory in Cape Town was sealed the final night by three Ben Stokes shutters, who also scored 72 of 47 balls in the second half.
This came after an excellent year of 2019, when he was named man of the match in the World Cup final and reached an incredible century to lead England to victory at the third Headingley Ash Test.
On Wednesday, he was named player of the year by the International Cricket Council.
"It's definitely the right decision," said Root. "For me at the moment he is the best player in the world.
"He is an invaluable member of our team as a senior player and an example."
Proteas to speed it up to Buttler
South Africa captain Faf du Plessis said his team is considering calling Dane Peterson, potentially in place of Dwaine Pretorius or Keshav Maharaj.
"We are considering looking at someone like Pato, but we haven't decided that yet," he said.
"A big question we would need to answer is 'who?' If you do that, you will have one less beater or spinner. You need a spinner in St George's Park and need more training. long, so it's not an easy decision. "
Speedy player Anrich Nortje said Buttler could face some hostile bowling in the third test after cursing Philander in Cape Town.
"It definitely takes one or two guys," said Nortje. "It's not something you can say in a microphone.
"This is for referees and whoever resolves it, but it makes the blood flow, and once we identify a moment, we'll probably try to revitalize it."