England will continue to monitor Jofra Archer, Stuart Broad and Jack Leach as the trio aim to prove they are fit to feature in the first Test against South Africa.

The three players were not involved in the warm-up fixture against South Africa A this week due to illness, leaving the tourists with a depleted bowling attack in Benoni.

Pace-bowling duo Archer and Broad, along with spinner Leach, have taken part in net sessions, however, and batting coach Graham Thorpe was able to offer a positive update after the game finished on Sunday.

England - who called up Craig Overton and Dominic Bess amid the illness issues - begin their series against the Proteas on December 26, with SuperSport Park in Centurion staging the first Test.

"We are going in the right direction," Thorpe told Sky Sports about the three players. "We had a little bit of [illness] going around at the start of the trip.

"The downside is the lack of match time for those guys, but we will have to keep assessing them over the next three days leading into the first Test.

"We've just got to factor in how they feel physically, then how much you feel they are confident going into, and performing well, in a Test match for five days."

While Archer and Broad were absent, England received a boost with the sight of James Anderson in action for a second time on the trip.

Making his return from a calf injury in the first Ashes Test at the start of August, the 37-year-old seamer recorded figures of 3-41 from 19 overs against South Africa's second string.

Thorpe acknowledged Anderson's presence brings some much-needed stability to captain Joe Root's line-up.

"It's phenomenal," the former England international said. 

"I think in 2004, which was my last tour as a player, Jimmy was just coming into the squad. To think he's still out there now, 15 years later, performing. It's great to have him back out there.

"As we saw today, he's very skilful, keeps it very tight and creates opportunities. That's the type of bowler we want over here."