Craig Beattie felt Hearts were lucky to be awarded their last-minute penalty against Celtic at Hampden, but the striker was confident he would score.
Referee Euan Norris pointed to the spot after the ball struck Joe Ledley's arm and glanced Victor Wanyama's hand.
Beattie told BBC Scotland: "For me, it's not a penalty. I would be very disappointed if my team went out of the cup losing to a penalty kick for that."
His strike from 12 yards set up a Scottish Cup final against Hibernian.
The former Celtic striker came on as a half-time substitute and made an immediate impact, sliding in a pass for Rudi Skacel to round goalkeeper Fraser Forster and open the scoring on 47 minutes.
Gary Hooper levelled with a header from an offside position with just four minutes remaining before Beattie slammed the ball home to settle the match in Hearts' favour.
It was Beattie's fourth goal in six games since moving to Tynecastle in February and sets up an all-Edinburgh final with Pat Fenlon's Hibs on 19 May - the first since 1896.
"What a game that is going to be,"Beattie told BBC Radio Scotland. "An Edinburgh derby in the Scottish Cup final - it's magnificent."
Speaking on Sportscene, Beattie spoke of the penalty incident where Ledley was penalised when Marius Zaliukas's shot from just outside the box smacked against the arm of the Celtic midfielder, who was positioned about three yards away, just inside the area.
"If your hands are away from your body, you're making your body bigger but I don't think he has done that," said Beattie.
And of the decisive kick itself, the striker added: "I had mentioned to David Templeton on the bench about a penalty. I was just preparing for every eventuality.
"I was surprisingly quite calm. I had run through the scenario of the penalty kick.
"That was pretty much exactly what I had planned in my head. I managed to execute it well."
Beattie, though, was adamant that Hooper's late equaliser should never have stood.
He said: "It was disappointing. Obviously he was offside. I don't think it was a difficult decision for the linesman [Willie Conquer]."
Manager Paulo Sergio saw his half-time switch pay dividends as Skacel, who was anonymous in the first half, burst into life with a goal and two shots that worried Forster.
Television replays showed that Hooper was in an offside position to nod Celtic level, but Sergio was unconcerned.
"My players were talking about it, but I don't want to criticise after a great performance from the officials," he said.
"We had four or five good chances to score in the second half and this victory has even more flavour because we were playing against Celtic, who are a very good team.
"It's a great joy to play a final against our rival and on that day we are going to fight for the victory.
"But, until that day, I'm going to focus on the next game and that is against Rangers."