Sunderland manager Martin O'Neill has been dealt a blow with the news that defender Phil Bardsley is set for a lengthy spell out through injury.
Bardsley, 27, made 29 starts for the Wearsiders in 2011-12, but has missed much of pre-season with an ankle injury.
The Scotland international was also forced to pull out of his country's squad for their friendly against Australia on Wednesday.
"Phil Bardsley has had an operation. That's a real blow for us," Sunderland boss Martin O'Neill confirmed to the club's official website.
The news could tempt O'Neill into pushing forth with a deal for Aston Villa fullback Stephen Warnock - with the Wearsiders having also been linked to Wolves defender Stephen Ward this week.
However, O'Neill had better injury news when it came to trio Stephane Sessegnon, David Vaughan and Wes Brown.
Sessegnon in particular has had a difficult pre-season with VISA complications forcing him to miss the club's recent trip to Helsingborg.
He then picked up an ankle knock which further disrupted his preparations, but his manager remains confident the Benin forward will be ready for an opening-day visit to Arsenal.
"Stephane has done a little bit of training this morning, and hasn't felt any effects," O'Neill said. "He hasn't been able to do that much but in the course of the next few weeks in terms of the sort of fitness level that he can attain, we hope he gets there pretty quickly."
O'Neill added: "Wes Brown is feeling a bit better but obviously getting a bit annoyed that injuries have plagued him. David Vaughan's making progress and he had an operation on his side to cure a problem and he's making good progress out there on the training field, but hasn't joined in with us yet."