Celtic were granted the opportunity to make a sixth substitution when St Mirren wing back Elvis Bwomono was forced off the pitch due to a concussion substitution.
After a collision with Yang Hyun-jun, St Mirren substituted Bwomono, allowing Celtic to make a concussion substitution themselves.

Confusion began to spread around the stadium, with Celtic assistant manager John Kennedy even explaining to a number of Celtic supporters why the Hoops were allowed to bring on a sixth substitute in the unusual circumstance.
It certainly won’t be a regular occurrence, but with Bwomono sustaining a head injury, it highlights the decision to introduce concussion substitutions as part of a trial in Scottish football in the 2020/21 season.
With head injuries a clear issue in football, the decision to implement the substitution encourages managers to substitute players who have suffered a head injury, even if they want to continue, without concern of using one of the five other substitutions they have to utilise.
With Celtic emerging 3-0 victors, today’s win is vital in putting pressure on city rivals Rangers, who play Ross County tomorrow at Dingwall.
The Hoops are now four points clear at the top of the Scottish Premiership with just five league games remaining.