Celtic's new Bulgarian winger Aleksandar Tonev faces a lengthy Scottish Football Association suspension if he is found guilty of racist abuse after an allegation from Aberdeen defender Shay Logan.

Aberdeen have made a formal complaint to the SFA after Logan claimed he was racially abused as he and Tonev had a coming-together during the second half of Celtic's 2-1 win at Parkhead on Saturday. Logan complained to the referee, Bobby Madden, and his own captain, Mark Reynolds, during the game. Tonev was making his Celtic debut and was substituted in the 70th minute. Playing on the left wing meant he was in direct opposition to right-back Logan.

Aberdeen manager Derek McInnes and SPFL match delegate John Connolly were informed of the allegation, which Tonev has denied. A Celtic spokesperson said: "We have spoken to the player and he has stated that the accusation made is not true."

When the complaint and the referee's report arrive with the SFA their compliance officer, Vincent Lunny, will investigate and could issue a notice of complaint against Tonev for "excessive misconduct". If so, Tonev will be asked to give his version of events and the SFA's judicial panel will have to adjudicate.

If found guilty Tonev would face a minimum four-game ban although the range of sanctions allows for a suspension of up to 16 games depending on the gravity of the circumstances. Aberdeen and the SFA refused to comment yesterday.

Meanwhile, Jason Denayer believes Celtic can go all the way to the Europa League final in Warsaw if Ronny Deila's squad plays to its potential. The 19-year-old defender, on loan from Manchester City, made the startling claim in the build-up to Thursday's opening group game against Red Bull Salzburg in Austria.

The bookmakers do not regard Celtic as a serious contender to make a mark on the tournament. Tottenham Hotspur, Napoli, Inter Milan, Sevilla, Fiorentina and Everton lead the market. Another eight strong teams will drop into the competition in the round of 32 after coming third in their Champions League groups. Celtic are currently priced at 100/1 to win the final on May 27.

Having scored in the weekend defeat of Aberdeen, though, Denayer was upbeat about what Celtic could achieve. "The Europa League is a big thing for me," said the Belgian defender. "There are different styles of player to face, so we have to face different challenges. We must concentrate on the Europa League and do all we can do in that competition. It all depends on us. If we play as we can, if we play to 100 per cent of our ability, we can go to the final. It's about us. Celtic is a big club with high expectations and we will try to meet them. I hope playing for Celtic can get me into the Belgian squad. If I can play regularly for Celtic in the Europa League that will help me with that objective. But my first objective is to be good for Celtic. After that, I can think about Belgium."

Celtic are resigned to being without winger James Forrest for another month. The 23-year-old's hamstring problems have kept him out since the game against Dundee United a month ago. Although he has done light work he remains well away from being able to make a return to full training.

The club are still unclear on whether Charlie Mulgrew will require surgery on the knee problem he picked up in Scotland's Euro 2016 game in Germany. Former defender Darren O'Dea is training with the fitness coaches at Lennoxtown but will not be rejoining the club. O'Dea, 27, was released by Metalurh Donetsk last month after spending a year with the Ukrainian club.