WILL GRIGG could be facing up to nine months on the sidelines as Sunderland’s medical staff look to resolve the striker’s long-standing knee issue.

Grigg is due to see a specialist tomorrow to assess a knee problem that has been troubling him for a number of weeks.

The best-case scenario is that scans reveal a soft-tissue injury, meaning the striker will be instructed to rest for around three weeks to give his knee a chance to settle before returning to action.

An alternative prognosis would see the Northern Ireland international told to rest up for a longer period of around three months before coming back into the first-team fold for the last couple of months of the season.

However, if keyhole surgery is required, Grigg will have to undergo a complex operation that will see him ruled out for the rest of the current campaign – and could also see him sidelined for the whole of the summer and the first two or three months of next season.

“He’s got a long-standing swelling of the knee,” said Sunderland head coach Lee Johnson. “I don’t think he’s been moving as well as he could have, or at least as well as I’ve seen him moving before.

“He’s going to see a specialist on Monday, and we’ll find out whether it’s three weeks, three months or nine months. I don’t think there’ll be any in between. It’ll either be rest for three weeks then have another go, rest for three months but still keep it non-surgical or we go down the surgical route.

“They’ll have to drill a hole effectively in the kneecap so it bleeds from in to out, to then form a calcification on the outside of the knee. Hopefully, it’ll be okay, but we’ve just got to touch wood and cross our fingers on it.”

Grigg’s prognosis is likely to influence Johnson’s activity in the transfer market this month, as Sunderland will be short of attacking options if the 29-year-old is ruled out for the rest of the season.

While Aiden O’Brien could play as a central striker if required and Benji Kimpioka should be returning from his own injury lay-off in the next few weeks, Danny Graham is currently the only real alternative to first-choice centre-forward Charlie Wyke.

Given that Sunderland will be playing three games a week for the vast majority of the remainder of the season, Johnson will be keen to ensure he does not leave himself short of a goalscoring threat.