Wales defence coach Shaun Edwards says flanker Dan Lydiate "probably" needs to play in the South Africa warm-up to be considered for the first Test.
But Edwards says Lydiate is so important that Wales may risk him in the first Test on 14 June even if the Racing Metro player fails to face Eastern Province Kings on 10 June.
Lydiate's hamstring strain kept him out of Friday's trial in Swansea.
Edwards also said prop Samson Lee (shoulder) should train this week.
With open-sides Sam Warburton and Justin Tipuric injured, British and Irish Lions back-row Lydiate could switch from blind-side to fill the gap at seven.
Versatile Scarlets back-rowers Aaron Shingler and Josh Turnbull have also played at open-side in the past, as has regular Wales number eight Taulupe Faletau.
But 35-cap Lydiate, 26, would appear to be favourite to cover for shoulder injury victims Warburton and Tipuric.
Wales' warm-up match against Eastern Province Kings in Port Elizabeth will be followed by Tests in Durban on 14 June and in Nelspruit a week later.
"I think Dan Lydiate probably needs a bit of a run-out before then [the first Test]," said Edwards. "So whether he's involved in the first game I'm not sure, but we'll decide that later.
"To give him confidence I think it would help him to have a little bit of game time. But Dan Lydiate is the kind of player who's an integral part of our team, maybe we'd even take a chance with him without playing in that game."
Scarlets tight-head Lee joined fellow Probables Jamie Roberts (shoulder) and Ken Owens (leg) in coming off in the trial against Wales Possibles at Liberty Stadium.
"We think they'll all be training later in the week and even Samson Lee is a positive scan," said Edwards.
"We'll re-assess him later in the week, but he seems pretty positive in himself. At first we feared the worst with Samson."
Gethin Jenkins (Cardiff Blues), Paul James (Bath), Adam Jones (Ospreys), Rhodri Jones (Scarlets), Samson Lee (Scarlets), Aaron Jarvis (Ospreys), Ken Owens (Scarlets), Matthew Rees (Cardiff Blues), Scott Baldwin (Ospreys), Alun Wyn Jones (capt, Ospreys), Luke Charteris (Perpignan), Jake Ball (Scarlets), Ian Evans (Ospreys), Aaron Shingler (Scarlets), Josh Turnbull (Scarlets), Dan Lydiate (Racing Metro), Taulupe Faletau (Newport Gwent Dragons), Dan Baker (Ospreys).
Mike Phillips (Racing Metro), Gareth Davies (Scarlets), Rhodri Williams (Scarlets), Dan Biggar (Ospreys), James Hook (Perpignan), Steven Shingler (Scarlets), Jonathan Davies (Scarlets), Jamie Roberts (Racing Metro), Cory Allen (Cardiff Blues), Alex Cuthbert (Cardiff Blues), George North (Northampton Saints), Jordan Williams (Scarlets), Matthew Morgan (Ospreys), Liam Williams (Scarlets).