The visitors took the lead in the 36th minute when Boyce, who netted both Hearts' goals on Saturday, fired powerfully home after playing a one-two with Michael Smith.

Henderson doubled the advantage three minutes later, calmly converting a corner at the far post.

And the hosts' task was made even harder soon after when Hendry was dismissed for a challenge on Andy Halliday.

Gnanduillet came on just before the hour mark, as a replacement for Boyce, and he got off the mark with six minutes remaining, blasting in a loose ball after MacDonald had denied Smith.

And the new recruit was celebrating a double in added time when he headed in a Walker corner.