The former Tottenham Hotspur forward is expected to return to Real’s team for the league derby against Atletico on Sunday.
If he comes through that he will be in the side to face Bosnia in Zenica on Oct. 10.
Chris Coleman’s Wales team need one point to qualify for France 2016 which would be their first appearance in a major finals since the 1958 World Cup in Sweden.
“If Gareth is fit to meet up with us I will look to play him in Bosnia. We need our strongest team on the pitch to get the result we need,” Coleman said.
“We need a point from two games and we want to take care of our own business.”
Wales, who are unbeaten on 18 points with five wins and three draws, top Group B by one point from Belgium who are four clear of Israel.
Bosnia have 11 points and can still finish third and claim a playoff place while Andorra are bottom having lost all eight matches.
Cyprus, the other team in the group, have nine points.
Wales host Andorra on Oct. 13.
Goalkeepers: Wayne Hennessey (Crystal Palace), Danny Ward (Aberdeen), Owain Fon Williams (Inverness Caledonian Thistle)
Defenders: Ashley Williams (Swansea City), James Chester (West Bromwich Albion), James Collins (West Ham United), Ben Davies (Tottenham Hotspur), Chris Gunter (Reading), Neil Taylor (Swansea City), Adam Henley (Blackburn Rovers), Ashley Richards (Fulham)
Midfielders: Joe Ledley (Crystal Palace), Aaron Ramsey (Arsenal), Joe Allen (Liverpool), David Vaughan (Nottingham Forest), Jonathan Williams (Nottingham Forest), Emyr Huws (Huddersfield United), Andy King (Leicester City), David Edwards (Wolverhampton Wanderers).
Forwards: Gareth Bale (Real Madrid), Hal Robson-Kanu (Reading), Sam Vokes (Burnley), Simon Church (Milton Keynes Dons), David Cotterill (Birmingham City), Tom Lawrence (Blackburn Rovers).
(Reporting by Mike Collett; Editing by Tony Jimenez)