Kelechi Iheanacho made a decisive impact off the bench as Celtic thrashed St Mirren 6–2 to secure their place in the Scottish Cup final on Sunday afternoon.

Featuring in his first Scottish Cup appearance, the Nigeria international was introduced in the 83rd minute, replacing Yang Hyun-jun, with the Hoops holding a narrow one-goal advantage.

Earlier, Daizen Maeda and Anthony Ralston had put Celtic two goals ahead at the break, but a brace from Mikael Mandron forced the tie into extra time.

The introduction of Iheanacho proved pivotal as Celtic produced a devastating burst in the first period of extra time, scoring four goals in just six minutes.

In the sixth minute of extra time, the Manchester City academy graduate rose to head home after James Forrest delicately lifted the ball into the area.

Luke McCowan made it 4–2 moments later, before Iheanacho struck again in the 101st minute, guiding a composed finish into the corner to effectively end the contest.

Benjamin Nygren then added further gloss to the scoreline, tapping home to complete an emphatic victory.

The brace takes Iheanacho's tally to six goals in 18 appearances for Celtic since his move from Sevilla last September.