Following the defeat to Manchester City, seven of the first team players have flown out to play for their nations, while Raul Jimenez has also travelled with the Mexico team where he will continue his rehabilitation for a groin issue.
Back at Compton, the players not called up are back in training as Bruno Lage puts them through their paces.
Among them is Costa who has joined full training with the squad for the first time this week.
The free agent signing spent his first week at Wolves doing separate sessions and joining in with warm-ups and small drills as he got to know his new team-mates.
Lage is aiming for the 33-year-old to be available from the bench against West Ham next week and the former Spain international has now joined full training in preparation.
Wolves have also been handed another boost as Traore makes his return from injury.
The winger missed the loss to City with an adductor problem but has made a swift recovery as he has also joined training.
Traore has largely been used as a substitute this season but his return is timely for a Wolves side needing attacking inspiration.
He is likely to be available for the West Ham fixture if he does not suffer a setback in his short injury comeback.