Rangers have suffered a hammer blow after boss Derek McInnes confirmed that club captain Lawrence Shankland could be out of action for up to four months.Shankland was forced off in the early stages of the 1-0 win over Motherwell at Ibrox last weekend, with subsequent tests confirming a torn hamstring which could keep him out until the turn of the year.The 31-year-old suffered a similar injury with Hearts last season and will now meet with a specialist to determine whether or not he needs surgery.Rangers were already reeling from the loss of Youssef Chermiti with a season-ending ACL injury – and Shankland will now join his fellow front man as a long-term absentee.The Scotland striker had started to find some form for Rangers, scoring three goals in two games prior to his injury, but McInnes will now move forward with Ryan Naderi, Kevin Kelsy and Bojan Miovski up front.Speaking ahead of tomorrow’s Premiership clash with St Mirren at Ibrox, McInnes said: ‘He’s had his scan with confirmation that he’s had a tear. It’s a 2cm tear and similar to the one he did previously at Hearts in January. Rangers striker Lawrence Shankland hobbled off in the 1-0 win over Motherwell on Saturday Shankland fired home a double against Falkirk last week but is now out for four months‘He’s actually in London now, getting an ultrasound scan, a follow-up scan, which is just to determine whether, with the specialist, he has surgery or whether he’ll just let it heal naturally like he did the last time.‘We will probably have a better idea in the aftermath of that scan and discussion with specialists just how long the injury is going to be.‘The little knowledge I have of it is that if he has the surgery then he might be an extra three or four weeks. But if he has a surgery, then it lessens a risk of it maybe happening again. Again, all these things will be confirmed probably in the next 48 hours or so.‘Unfortunately for us and Lawrence, it’s a significant amount of time out. I think best case scenario, three months. Probably worst-case scenario, about four months.‘We just need to support him as we do with all our injured players, but having him and Youssef out, guys who guarantee you goals at Premiership level, there’s no doubt it’s a blow for us.‘But their disappointments are other people’s opportunities as you’ve seen, even from Saturday, Ryan getting his goal and Kevin getting introduced.‘We have Bojan Miovski, who knows his way about the Premiership as well, so it’s not all doom and gloom on that front, but it is disappointing news.’McInnes revealed that a pause in play due to a malfunction with VAR may have been partly responsible for the injury.When asked how Shankland had responded given it was a recurrence of the same injury he suffered at Hearts last season, the manager continued: ‘Yeah, you could tell the disappointment. I could see from the way he walked off at the weekend that he knew it was something significant. Rangers manager Derek McInnes oversees training ahead of the league clash with St Mirren‘It happened right when the VAR communications had broken down and there was all that standing about.‘I think it was about two-and-a-half minutes of standing around and then it was his very first sprint after that when he did it.‘It’s just one of those things you have to deal with when it comes to injuries. He was starting to find his stride here and had scored some important goals for us. But that is football unfortunately. He’s in good hands here medically and there’s still going to be a big part of the season left when he comes back into action.‘He’s got to hold on to that and be ready to play his part in the second half of the campaign.‘As I’ve just said, there are three boys there. Ryan was a significant investment by the club last season, albeit coming from a lower level. He’s a handful and I think when he plays, particularly with a partner, he does the job.‘Kevin is one the club spent a significant amount of money on. He’s still young and it’s a big step coming here, but we believe it’s the right step for him.‘Bojan’s goals-per-game ratio in Scotland is very, very strong and throughout pre-season he’s been brilliant. There was a point where it looked as though he might be going elsewhere, but that’s football.‘Opportunities come along and I’m glad these three lads are in the building. It’s not always the case that you’ve got such good options when you get two significant injuries in one area of the pitch, so I feel fortunate we’ve got them.’