Hearts started with an unfamiliar back three with Michael Smith central, and the experienced defender's ability in possession was evident as he stepped forward confidently and fired a fierce effort just wide from 35 yards on eight minutes.

The game burst into life after the Buddies had their first chance on 22 minutes when Ilkay Durmus' excellent whipped cross was sent narrowly wide by the on-rushing Kyle Magennis.

As the visitors reshuffled their defence after Halkett limped off to be replaced by Christophe Berra, St Mirren thought they had taken the lead but Tony Andreu's goal was controversially ruled out.

Magennis' deflected shot found the Frenchman unmarked just inside the box and he fired past Pereira but after initially not raising his flag, linesman Douglas Ross flagged for offside after deliberation with referee Andrew Dallas.

Levein will be concerned with Hearts' growing injury crisis but both his substitutes combined to almost put the visitors in front. Andrew Irving's left-footed deliveries twice found the imposing figure of Berra, who forced Vaclav Hladky into good saves.

The second half continued in the same vein as the first with both sides restricted to long-range efforts and speculative crosses.

The impressive travelling contingent screamed for a penalty when Irving tumbled over a challenge in the area on the hour but he was fortunate not to be cautioned for simulation.

The visitors spurned a glorious opportunity to claim all three points on 73 minutes. Uche Ikpeazu's strength and perseverance enabled him to hold off a defender before clipping a delicate ball to MacLean, but he somehow fired over from just six yards out.

With virtually the last kick of the game, Jonathan Obika almost won it for the hosts but his left-footed effort sailed wide.