Sunderland striker Fabio Borini has been ruled out for three months with a groin injury.
The 25-year-old Italian suffered a torn ligament taking a free-kick in the 1-1 draw with Southampton last Saturday and had to be replaced.
It leaves the club with Jermain Defoe, 33, as the only recognised striker alongside 17-year-old Swede Joel Asoro.
Sunderland missed out on the signing of Norwich forward Steven Naismith, 29, on transfer deadline day.
Sunderland’s other forward options are 22-year-old winger Duncan Watmore and Manchester United’s on-loan winger Adnan Januzaj, after Jeremain Lens was loaned to Fenerbahce.
The Black Cats also missed out on re-signing midfielder Yann M’Vila from Russian side Rubin Kazan, who spent last season on loan at Wearside.
But they have a pre-contract agreement in place allowing the two clubs to negotiate again in January.
M’Vila posted on social media that he was at Heathrow on transfer deadline day, but the two sides could not agree on a fee for a permanent transfer, with Kazan wanting 10m euros (£8.4m).
Sunderland confirmed a move for Boavista goalkeeper Mika was also unable to be completed before the transfer deadline on Wednesday.
They have appealed to football’s world governing body Fifa after the paperwork was held up at the Portuguese end.
First choice keeper Vito Mannone was scheduled to be out for three months after tearing elbow ligaments, but tweeted on Wednesday that he had an operation and would be back “sooner than expected.”
Mannone’s deputy Jordan Pickford has returned from international duty with England’s Under-21s with a slight thigh strain, although he is expected to be fit for the home clash with Everton on September 12.
Sebastian Larsson is also injured, alongside key midfielders Lee Cattermole and Jan Kirchhoff.
David Moyes was only appointed Sunderland manager on 23 July and lost his first two Premier League games, including the 2-1 defeat by Middlesbrough.
He bought in defenders Donald Love and Paddy McNair from Manchester United for a combined £5.5m, Papy Djilobodji from Chelsea for £8m, midfielder Didier Ndong from Lorient for £13.6m and completed the loan signings of Jason Denayer, Javier Manquillo and free agent Steven Pienaar.