Celtic forward Shaun Maloney insists his team-mates cannot blame anyone but themselves for their defeat to Hearts.
The Bhoys missed the chance to overtake Rangers at the SPL summit on Wednesday after suffering a 2-0 defeat at Tynecastle.
Elsewhere, Rangers were being shocked at home by Hibernian and Maloney is gutted Celtic were unable to capitalise on their slip-up.
Maloney admits his personal performance was not up to scratch and that conceding the first goal of the game was their undoing.
"I think when we come in at the end of the game and we find out the other results it probably was a missed opportunity, but I think we need to look at our own performances before we start counting on Rangers getting beaten," he told the Evening Times.
"I myself probably didn't produce enough going forward for the team, and attacking-wise we weren't quite good enough, especially in the first half.
"That is the reason why we went in one down and, in the end, I think it is that which has probably cost us the game."
Celtic manager Neil Lennon felt referee Craig Thomson influenced the match after sending off Joe Ledley, while he also turned down their penalty shout against Ryan Stevenson.
Maloney thought the Bhoys would be given a spot-kick for Stevenson's handball and he also felt the decision to dismiss Ledley for his overzealous tackle on Ian Black was harsh.
"At the time I thought it was a penalty," he said. "I was about 10 or 15 yards away and I thought it was a penalty although I haven't seen any replays yet.
"I also thought the sending-off was harsh. I spoke to the referee and said I didn't think it was a sending off, I didn't think it was overly reckless."