Hearts manager Craig Levein lamented his side's lack of cutting edge as the Premiership leaders fell to a 1-0 home defeat to Kilmarnock.

The Tynecastle outfit had looked more likely to break the deadlock, having dominated possession for most of the match, but they were undone by Ross Millen's 73rd-minute strike.

Hearts have now failed to score in their last four matches in all competitions and will be knocked off top spot - a position they have held since the opening day of the campaign - if Celtic collect at least a point at Livingston on Sunday.

Levein, who is without strikers Steven Naismith and Uche Ikpeazu through injury, as well as defenders Christophe Berra and John Souttar, admits his team did not show enough ingenuity in the final third.

He said: "There are loads of ways of losing a match but that's the most frustrating, that you have loads of possession and dominate the play.

"We should have been better in the final third but to lose that way makes me feel really frustrated.

"We've created chances - the players who we have out injured, I think it would be easier to score goals if we had them in the team - everybody knows that.

"At the same time, we need people to step up and at times like this, put the ball in the back of the net.

"That isn't just our strikers or midfielders, the centre-backs had opportunities as well.

"It's a little bit frustrating but I have to be mindful that we've had a difficult period. We can't continue to go through the league season winning every match."

Hearts did have the ball in the net in the second half but Steven MacLean's effort was ruled out for offside.

Kilmarnock right-back Millen - making his top-flight debut - then drilled a low shot under Hearts goalkeeper Zdenek Zlamal in the 73rd minute.

Killie manager Steve Clarke, whose side have climbed to third with a 24-point haul - two adrift of Hearts, said: "I think we should have more points.

"I think we should be higher in the league. I am probably a little bit disappointed with our points tally to be honest.

"But it is nice at this stage of the season to be so far away from the bottom two and if we can pick up a lot more points over the next eight matches over the winter break then maybe, if we do it properly between now and the winter break, then we can think about mounting a serious challenge for the top six again."

Clarke also confirmed that he expected Stephen O'Donnell to pull out of the Scotland squad after the defender sustained an injury in training.

He added: "Stephen is injured, he got a hamstring injury in training through the week and I would say 99.9 per cent out for Scotland."