Juventus striker David Trezeguet may have to undergo an operation on a troublesome shoulder injury and could face a four month layoff, his coach Fabio Capello said on Sunday.

The France international was substituted half way through Juve's 1-0 win at Udinese on Sunday after landing badly on his shoulder.

"The shoulder keeps coming out," Capello told Italian television.

"At this point he needs to decide whether to have an operation or not. With an op he would be out for four months but it is his decision," added Capello.

The injury puts Trezeguet's involvement in France's World Cup qualifiers against Ireland and Cyprus in serious doubt.

The striker's problem comes at a bad time for Juventus who have forward Alessandro Del Piero sidelined for at least two weeks with an achilles tendon injury.

On Sunday Trezeguet's place alongside Zlatan Ibrahimovic in attack was taken by Uruguayan Marcelo Zalayeta who headed the winner for the Serie A leaders.

If Trezeguet were to have an operation, however, Capello would be short of cover in attack.