Mario Balotelli could make a surprise debut for Manchester City on Thursday night against Timisoara in the Europa League.
It was widely expected that the former Inter Milan striker, who joined the club last week, arrived too late to be included in the squad.
However UEFA confirmed on Tuesday morning that Balotelli still had a chance of playing in the play-off first leg-match as one change can be made to the original list.
City, though, face a race against time as the 20-year-old's registration needs to approved by both the Football Association and UEFA before midnight on Wednesday.
UEFA article 18.14 states: "For the three qualifying rounds and the play-offs, one player on List A may be changed until 24.00 CET on the day before the relevant first-leg match, provided that the club's national association confirms in writing that the new player is eligible to play at domestic level at this time."
The squad are due to travel on Wednesday with reports in Romania stating that Timisoara are on 100 euros a man to beat City and progress in the competition.
Balotelli can be a big hit in the Premier League, according to Chelsea boss Carlo Ancelotti.
Blues manager Ancelotti is an admirer of the 20-year-old, who arrived at Eastlands in a reported £22.5million deal.
"Mario is a great player who comes into a team that was already strong last year, which has improved in the transfer window," Ancelotti told Italian newspaper Il Corriere dello Sport.
"Balotelli is a player suited to this league. He is very strong physically and technically. He will slot into his new team in a hurry."
Ancelotti guided Chelsea to the Double in his first season last year, and saw his team open the new campaign with a 6-0 thrashing of West Brom at Stamford Bridge.
The Italian believes if Roberto Mancini can gel all of his multi-million pound talent together, then City - who drew 0-0 at Tottenham on Saturday - could challenge for the championship.
"If he manages to assemble very strong players like Yaya Toure, [David] Silva and Balotelli in a hurry, then yes, City will be ready to fight for first place," Ancelotti said.
