Hearts boss Paolo Sergio has bemoaned his side's recent run of bad luck after they were beaten 4-0 at home to Celtic.
Stephen Elliot appeared to open the scoring for the home side with a headed effort in the opening minutes. However, with the ball adjudged to have not crossed the line, Celtic were able to counter and score at the other end.
"We have been very unlucky with some decisions in the last three games," he said. "The referee didn't see it tonight.
"We should have had a clear penalty in the cup game against St Johnstone. At Inverness we should have had a penalty. Everyone saw it on television but no-one on the pitch.
"We were very unlucky but that's football, there are days like this."
Hearts have now slipped six points adrift of third place in the Scottish Premier League.