Archer bowled around seven overs in the nets on Wednesday as he continues his comeback from an elbow injury.

The 24-year-old, who bowled 36 overs in the first-Test defeat, missed the next two Tests, which England won.

"[Archer] bowled well and the pain seems to be decreasing, which is good." Thorpe said.

"We're just getting his rhythm; his bowls were good."

Mark Wood, who played his first Test in a year at Port Elizabeth, is not certain to be available on Friday.

Thorpe added: "We have to see how Mark Wood comes up as well. He has not played back-to-back Test matches for a long time.

"Fingers crossed we can pick from a full set - that's what you want."

Even though England go into the fourth Test at the Wanderers with a 2-1 lead, Thorpe said the tourists were not getting carried away.

"We spoke after the Port Elizabeth Test but we want to go in with a clean slate," he said.

"We enjoyed that victory but we start again - we want to be consistent."