Sunderland rocked by double injury blow - this is when Ross Stewart will return

Stewart picked up a thigh issue during the warm-up ahead of Monday’s 1-0 defeat at Middlesbrough, meaning he was taken out of the starting XI.

Speaking to the club’s website, Mowbray said: "Ross will be out for six to eight weeks - it could be a little longer, but that will depend on his rehabilitation and the way his body reacts.

"He's a really positive guy and we hope that he will be a quick healer, so we will take it game by game and hopefully he returns quickly.”

He added: "It is a blow and now we have to find a way to score the goals, but we will be positive and we will not be all doom and gloom about how we are going to win games and score.

“There are players within the squad who are capable of stepping up and our job is to find a way to win, so that's what we will do."

Cirkin was also forced off during the match against Boro with a hamstring problem, yet the defender should be available after the upcoming international break.

"Dennis will be out for one to two weeks and it is as slight an injury as you will see,” said Mowbray. “He should be back in action within a fortnight.”

Sunderland will host Millwall at the Stadium of Light this weekend, before back-to-back away games at Reading and Watford next week.

There will then be a two-week break for international fixtures before Mowbray’s side host Preston on October 1.

Stewart was Sunderland’s top scorer last season with 26 goals, and has already scored five times in seven Championship appearances this campaign.

The Scot was forming a promising partnership with new signing Ellis Simms, who is on loan from Everton, yet the former’s absence will leave the squad extremely light of attacking options.

Sunderland’s Sporting Director Kristjaan Speakman has previously said the club are unlikely to add free agents to their squad after missing out on more signings on transfer deadline day. Still, injury setbacks could force the Black Cats to re-think their plans.