Jack Ross looking to add to attacking options after injury to Christian Doidge

That leaves the Edinburgh club light on numbers in attack, with Scotland international Nisbet the only other experienced forward.

Ross said: "We'll need to replace him. It's an area we needed to strengthen before Christian's injury but this heightens the need for reinforcements.

"It's likely to be three or four months before he even returns to training so it's a serious blow for us and for him as well.

"He was back in contention for the Wales squad and that's been a big driver for him.

"He's been terrific for us and I'm so disappointed for him."

Asked if Doidge's injury influences the club's efforts to hold on to Nisbet during the current transfer window, Ross added: "I don't want to lose my best players and the need becomes more pressing in the forward areas because we don't have a multitude of options."

It was a productive day on the pitch, however, as Magennis and Nisbet scored second-half goals to take Hibs into the quarter-finals of the League Cup.

Kilmarnock, now plying their trade in the Championship, had a great chance through Scott Robinson in the first half, while Liam Polworth crashed a shot off the underside of the bar.

Kilmarnock manager Tommy Wright said: "I'm obviously disappointed to go out but there were aspects of the game which were pleasing.

"We played well, particularly in the first half and we probably should have been ahead because we had the better opportunities.

"Scott Robinson had a great chance and maybe when he's properly up to speed with speed and match fitness, he takes the ball round the goalkeeper."