AC Milan forward Antonio Cassano was feeling "well" after undergoing heart surgery on Friday, his club said on their website.
The Italy international, who was diagnosed with a heart defect this week after falling ill following last Saturday's victory at Roma, underwent a 35-minute operation and is likely to miss much of the season.
"This morning heart surgery was performed on Antonio Cassano to close his patent foramen ovale," the club, who entertain Catania on Sunday, said. "He is well and in the next few days will take tests that will determine when he will be able to go home."
Leaders Juventus are at full strength for Sunday's testing trip to Napoli with defender Stephan Lichtsteiner expected to shake off a foot injury and midfielder Emanuele Giaccherini back in training.
Juve, whose victory at Inter Milan last weekend stretched their unbeaten start this season under new coach Antonio Conte to nine matches, go into Serie A's big match of the weekend a point above Udinese and Lazio.
"The club that wins the title will be an unpleasant side," Conte told Italian talk show Le Iene. "Recently Juve have become too likeable. The wish now is to get back to being less pleasant."
Fifth-placed Napoli welcome back skipper Paolo Cannavaro but must do without Uruguayan midfielder Walter Gargano for Sunday's visit of Juventus.
The centre-back, who missed Wednesday's 3-2 Champions League defeat at Bayern Munich through suspension, could line up in defence alongside Federico Fernandez - scorer of two headers in the midweek loss - should Salvatore Aronica fail to recover from a pelvic injury.
Struggling Inter Milan have more injury worries ahead of Sunday's trip to Genoa.
After the news earlier this week that Brazilian defender Maicon would be out for a month with a thigh injury, midfielders Wesley Sneijder, Esteban Cambiasso and Dejan Stankovic are all fighting to be fit for the clash with 11th-placed Genoa.
Centre-back Walter Samuel, who scored in the Champions League victory over Lille on Wednesday, returns to league action after a three-week layoff for the Nerazzurri, who have conceded 16 times this season and lie fourth from bottom.
Palermo President Maurizio Zamparini has given coach Devis Mangia a vote of confidence ahead of Saturday's home match against Bologna following the shock resignation of sporting director Sean Sogliano on Tuesday.
Zamparini, who confirmed his no-nonsense reputation earlier this season by sacking Stefano Pioli before he had led a Serie A match for the Rosanero, has replaced Sogliano with Luca Cattani.
"I had a wonderful conversation with Mangia and have given him my full backing," he told a news conference. "I hope he will be Palermo coach for a long time."
AS Roma striker Fabio Borini could be out for a month after picking up a thigh strain in last Saturday's defeat by AC Milan.
The Giallorossi, who have slipped to 13th after losing three of their last four games, travel to Novara on Saturday.
