Captain Siya Kolisi, Ox Nche and Jaden Hendrikse are desperate for game time after title-holders South Africa arrived in Britain on Sunday to continue their 2023 Rugby World Cup preparations.
The trio missed the first four matches of the Springboks season in July and August against Australia, New Zealand and Argentina (twice) due to injuries and a bereavement.
There are two more chances for them to demonstrate fitness and form as South Africa face Wales in Cardiff on 19 August and New Zealand in London on 25 August in warm-up internationals.
Kolisi suffered a serious knee injury in April, with medical experts initially despondent about his chances of featuring in the 8 September - 28 October World Cup in France.
But the flanker has defied the odds, making a quicker-than-expected recovery and said this weekend that he was "over the injury and wanted as many minutes as possible on the field".
If fit, Kolisi is a certain back-row starter in the World Cup opener against Scotland on 10 September, probably with fellow flanker Pieter-Steph du Toit and No 8 Duane Vermeulen.
Prop Nche, who will contest the loose-head place with Steven Kitshoff, sustained a chest injury while training for the season opener against Australia.
Scrum-half Hendrikse battled a shoulder injury and then left the Pretoria training base temporarily to mourn the loss of his father, Brian.
Faf de Klerk, one of 21 Springboks from the 2019 World Cup-winning squad in Japan who are going to France, is the first-choice scrumhalf.
But it is hard to separate expert box-kicker Hendrikse, dynamic Grant Williams and experienced Cobus Reinach in the contest to be the reserve No 9.
In an unexpected move, head coach Jacques Nienaber chose four scrumhalves rather than the traditional three, but several can perform dual roles.
Nienaber says De Klerk can stand in for Manie Libbok – the only fly-half specialist in the squad with first-choice Handre Pollard ruled out by a calf injury.
Williams, who is recovering from concussion, can also operate on the wing in an emergency, which could give him a slight edge over Hendrikse and Reinach.
After wholesale changes – nine and 13 respectively for the two clashes with Argentina – Nienaber says there will be fewer for the matches against Wales and New Zealand.
"There will be less chopping and changing from now on as we try to build more combinations," said the coach who leaves the Springboks after the World Cup to join Irish outfit Leinster.
"We have two warm-up matches to help us build combinations and fine-tune the areas of our game that need improving. We are by no means the final product at this stage."
After playing New Zealand at Twickenham, the Springboks head for the Mediterranean island of Corsica to continue preparing for the title defence.
On 1 September they head north to the French city of Toulon, then launch their Pool B campaign against Scotland in Marseille.
The Springboks also face section outsiders Romania, Six Nations and Grand Slam champions Ireland and physically formidable Tonga in the quest for a top-two finish and a quarterfinals slot.
Barring stunning results in Pool A, three-time world champions South Africa will tackle either France or New Zealand for a place in the semifinals of the global showpiece.