Jamie McGrath could be a doubt for next month's World Cup qualifier with Portugal after the St Mirren midfielder was stretchered off in the 2-1 home defeat against Rangers.
Compatriot Connor Ronan opened the scoring for the home side with a cracking effort from 30 yards, but two goals shortly before the interval from Kemar Roofe (penalty) and Alfredo Morelos swung the game in Steven Gerrard's side's favour.
With Portugal visiting Dublin on 11 November and a trip to Luxembourg three days later, Republic of Ireland manager Stephen Kenny will have watched on nervously as McGrath was stretchered off in the final 10 minutes at St Mirren Park with a hip issue after going down away from the ball.
Having used all three substitutes, the home side had to finish the game and its seven added minutes with 10 men. The 25-year-old has started two of the last three games under Kenny, including the most recent 4-0 win over Qatar.
St Mirren boss Jim Goodwin said: "We are not sure at the moment but Jamie wouldn't go down and certainly wouldn't come off on a stretcher if it wasn't serious.
"He will go for a scan (on Monday) and we will say our prayers that hopefully it is nothing too serious.
"Hindsight is a great thing and now we wish we would have taken him off immediately but we didn't realise it was as serious as it was."
The victory moved champions Rangers three points clear at the top of the table.
On a blustery day in Paisley, the home side stunned their visitors with an outstanding strike after just four minutes.
Gerrard's men recovered to eventually level in the 41st minute through a Kemar Roofe penalty, before Colombia international Morelos, out of sorts recently, headed the visitors in front two minutes later with a landmark goal.
The second half was less eventful, but it ended in a first defeat in seven for Jim Goodwin's side, who had started so confidently and were never out of contention.
Ahead of the visit of Aberdeen on Wednesday, Rangers are three points clear of Hearts and Dundee United and, perhaps more importantly, four ahead of Old Firm rivals Celtic, who have found form with four straight wins.
It was another test for Rangers after a crucial 2-0 Europa League win over Brondby at Ibrox on Thursday and they did enough for the win after a slow start.
The visitors were still trying to get to grips with the game when Ronan got away from Gers midfielder John Lundstram and fired a curling shot from 30 yards high past the diving Jon McLaughlin, in for Allan McGregor.
A St Mirren fan came out of the crowd to join in the celebrations but was dumped on his backside by unimpressed Saints defender Conor McCarthy.
Rangers could not find a rhythm, although in the 24th minute home goalkeeper Jak Alnwick saved a powerful Connor Goldson header from a James Tavernier corner, clutching another header from the Gers defender minutes later.
In the 35th minute Ianis Hagi had his second attempt on goal, which went wide.
However, when he was tripped just inside the box by Saints midfielder Alan Power, who had given the ball away, referee Steven McLean pointed to the spot.
Roofe slotted the penalty past Alnwick, who went the right way, and then there was bedlam when Morelos - a fan favourite since signing from HJK Helsinki in 2017 - headed in a Tavernier cross which McCarthy missed, jumping into the Gers fans behind the goal to earn a booking.
Just before the break Alnwick dived to push a Hagi shot from distance and then dived to save a Tavernier header from a Borna Barisic cross early in the second half.
Fashion Sakala replaced Morelos in the 69th minute after the Gers striker had missed the target with another drive.
With McGrath off and all their subs used, St Mirren finished the game with 10-men as Rangers assumed control at the top of the table.