Fiorentina's 5-2 victory over Debrecen in the Champions League on Wednesday came with a heavy cost as key striker Adrian Mutu suffered a worrying knee injury.

The Romanian striker, who moved to 10th place in the club's all-time goalscorer's list when he netted his 58th goal against the Hungarians, appeared to pick up a knock in the first half but carried on until the end and could now pay the price.

Mutu will certainly miss Sunday's visit to Udinese and could face up to a month on the sidelines after surgery.

Viola patron Diego Della Valle, brother of club president Andrea Della Valle, was giving little away when asked if the problem was bad enough to tempt the club into the January market.

He said: "Mutu is injured but we hope it will heal and he will get back soon. We will talk about the transfer market but you would need to ask my brother about that."

Mutu's absence should be at least partly compensated by the expected return of Montenegro forward Stevan Jovetic, who has missed the last two matches through injury but has been back in training this week.

Jovetic has not scored since his match-winning double against Liverpool in last month's Champions League clash but will be expected to shoulder much of the burden in the final third.

His second against the Reds was his fourth goal in three matches but he followed that hot streak by going five games without finding the target for club and country before his injury intervened.

Udinese, meanwhile, are looking to continue their upturn in form after putting three consecutive defeats behind them to claim an impressive victory over Roma followed by an away draw at Chievo last time out.

Bianconeri defender Christian Zapata believes his team can continue improving to record an important victory over

their visitors at the Stadio Friuli.

The Colombian believes coach Pasquale Marino has pulled together the strongest Udinese outfit since he joined the club in 2005 and has backed them to treat the home fans to a big result.

"We must not allow Fiorentina to play, because they know how to move the ball around well," said Zapata.

"When we play the Viola, we can pick up the points. This is the strongest Udinese side I've played for and we can do well."

Fiorentina head into the match in fifth place but such is the tight nature of Serie A this season that just three points separates them from Cesare Prandelli's 13th-placed side.

If they are to upset the rankings then experienced striker Antonio Di Natale could be the key, with nine goals from his 11 outings to date.

Despite that fine record he is goalless in his last four Serie A matches, a pattern he will be keen to end against the Viola.