Wigan have been granted international clearance for French midfielder Mohamed Diame.
The 22-year-old agreed personal terms and put pen to paper on a three-year contract at the DW Stadium earlier in the week.
After being registered to meet all the Premier League deadlines on Friday, the club received the green light in time to allow him to play in Saturday's match against Manchester United.
Manager Roberto Martinez said: "Credit to Rayo Vallecano, we were not sure if he was going to be eligible.
"But they have pulled out all the stops at their end to get the deal rushed through in time."