Swansea's record signing Borja Baston will be prevented from making his debut against Hull on Saturday after being injured in training.
The £15.5 million arrival from Atletico Madrid missed the opening-day 1-0 Premier League victory at Burnley last weekend as the game came only two days after he joined Swansea.
Borja, as he is known, was given extra time to build up his fitness ahead of playing some part at the Liberty Stadium this weekend.
But the 23-year-old will not be fit for Hull's Premier League visit after suffering a leg muscle injury.
"Borja's problem is a little one but he is not available,'' Swansea manager Francesco Guidolin said at his prematch news conference. "He has a muscular injury in the right leg.
"I hoped to have him in this period, but it is not possible. Perhaps I will have him on Tuesday at Peterborough [in the EFL Cup], but if it is not possible it is not possible.''
Guidolin also confirmed that Jack Cork will take over the captaincy should Leon Britton miss out against Hull.
Britton wore the armband at Burnley following Ashley Williams' departure to Everton but has been struggling with illness this week.
Jordi Amat and Federico Fernandez teamed up successfully at centre-back to shut out Burnley at Turf Moor with Williams' eight-year Swansea stay at an end.
But Swansea are still determined to strengthen in that department before the transfer window closes on Aug. 31.
"I am optimistic [for a new central defender],'' said Guidolin. "I have spoken frequently with the chairman [Huw Jenkins]. We haven't rushed. We have a shortlist of players. We have to decide without rushing, we are working on this.''
Guidolin -- who confirmed that out-of-favour pair Marvin Emnes and Franck Tabanou could depart Swansea before the end of the transfer window -- lost experienced players this summer with Williams, Bafetimbi Gomis and Andre Ayew leaving the club.
But he said that signing younger players to replace them was something he was comfortable with given his past experiences in his native Italy.
"I was used to this at Udinese,'' said Guidolin. "Every year we changed a lot of players, the best go, the young players arrive. I am used to working in this way.
"I was happy last season, at the moment it is the same with this group. It is different, but I am happy. There is a good feeling between me and my players.''