Hearts manager Paulo Sergio is frustrated his side squandered a winning position as St Mirren forced a Scottish Cup quarter-final replay.
However, he has promised his side will be ready for the resumption of battle in Paisley on Wednesday, 21 March.
"We could have killed the game and made it 3-1 three or four times, but we didn't, and lost a stupid goal. Unbelievable," he said.
"Maybe St Mirren deserved a second game. We'll go and fight for the win."
The Tynecastle side were under pressure from the off as Danny Lennon's side took the game to their Scottish Premier League rivals.
Graham Carey broke the deadlock for the Paisley side before Hearts found their stride and netted through Craig Beattie - making his first start - and Rudi Skacel.
However, a late own goal from Marius Zaliukas levelled the scores, although Hearts will feel aggrieved over a Beattie strike before half-time which was unjustly ruled out for offside.
Sergio did not want to discuss the controversy, but said: "I believe it was a great match, a fantastic afternoon for those who saw the game.
"I believe that St Mirren were the best I have seen them at Tynecastle in the first 30 minutes. They were very well in the game, so after the first 30 minutes of the game was when we started playing and returned to the game."
The Portuguese manager substituted midfielder Adrian Mrowiec for Skacel after Hearts' equaliser, and the Czech went on to net his side's second goal, but it was not part of the plan.
"I was going to substitute Mrowiec before the goal anyway," said Sergio.
"The problem was not just Adrian, it was Ryan McGowan and two or three others. I believe it was a bug in our dressing room. Adrian was not feeling well so we had to change what we planned during the week."