Sunderland striker Fabio Borini faces up to three months on the sidelines after tearing his groin on his comeback from a toe injury, Press Association Sport reports.
Borini, 25, is said to have torn an adductor muscle while taking a free kick during Saturday's 1-1 Premier League draw at Southampton.
Although the injury is a major blow, Sunderland have allayed fears that the Italian could miss up to six months and remain hopeful that he will be back in fewer than three.
It is a setback for manager David Moyes, who spent the final few days of the summer transfer window working with chief executive Martin Bain to land the players he needs to avoid another relegation scrap.
Borini joins long-term absentees Vito Mannone and Sebastian Larsson in the treatment room, while Lee Cattermole and Jan Kirchhoff have not managed a single appearance between them so far this season.
The Italian spent the 2013-14 season on loan at the Stadium of Light from Liverpool and helped the Black Cats reach the Capital One Cup final, in which they were beaten 3-1 by Manchester City after he had given them a first-half lead.
He returned to Anfield determined to force his way into the starting XI but left for good in August 2015 when he completed a move to Wearside for an initial £8 million.
Meanwhile, Mannone's deputy, Jordan Pickford, has returned from international duty with England's under-21s with a slight thigh strain but is expected to be fit for the home clash with Everton on Sept. 12.