Fiorentina fans should treat controversial former star Mohamed Salah with indifference rather than jeer him, head coach Paulo Sousa has suggested.

The Serie A leaders have launched a FIFA complaint against Chelsea over the Egypt international, who opted not to complete an 18-month loan stay in Florence.

Salah instead joined Roma on loan for the 2015-16 season, a move which has since been made permanent, with Fiorentina unhappy because they believe he should have remained with them for an additional year as part of the terms of the deal that saw Juan Cuadrado sold to Chelsea.

Salah makes his first return to Fiorentina in Roma colours in a big Serie A game on Sunday which sees first meet second in the table and Sousa advised greeting the 23-year-old with silent treatment.

"It is normal for a player to be jeered when he faces his old club, but often indifference is a far stronger message than jeers," Sousa said.

"Our fans should use their energy towards cheering us on. They will of course make their own decisions and express themselves as they see fit. 

"Despite everything against Napoli, our fans supported us to the end and this makes me very proud to be in charge of this club."

Fiorentina have suffered 2-1 defeats in their last two matches – the loss at Napoli last weekend and a shock home Europa League setback against Lech Poznan.

"Napoli and Lech were two very different games," added Sousa. "In Europe we struggled on the transition from defence and this allows our opponents to score from set plays."

Sousa insisted Roma should definitely be treated as Scudetto contenders this season but wants his side to go all out for victory against a visiting side who sit one point behind them.

"A victory is worth double, seeing as we are ahead of Roma in the standings," added the former Basel boss. "We have a few issues at the moment, but we can fight it out with anyone.

"The Giallorossi have a squad that allows them to win the Scudetto and they invested for that goal over the summer."