Peacock crashed over from close range following Sinfield's kick from a 20-metre restart which won Rhinos a scrum near half-way.

The 76th minute try broke Harlequins' hearts after the Londoners had stormed back from 24-4 down to lead 26-24.

Leeds looked to be heading out, but Peacock, pictured with Sinfield, said: "We always back ourselves to win games.

"We've got some talent in the team and some great thinkers. Kevin is the fittest player in the team and probably the smartest as well. He came up with a massive play to get us down the other end of the field."

Peacock's try was crucial to Rhinos' season, but he said: "I hope in my career I score a lot more important tries!

"But it needed to be scored, otherwise we're out of the Cup. I think there's only Keith (Senior) in the squad who has played at Wembley.

"It is a fantastic venue, the Challenge Cup final has a great tradition and we want to get there."

Of his 80 minute stint, in 80 degree heat, Peacock added: "I feel all right.

"I try not to go crazy and do as much work as I normally do and it has kind of worked out for me.

"I feel like I've got over the Easter period, I am feeling fit again, I have got some energy in the tank and I felt good out there.

"It was hot, but it wasn't as hot as it was when we played in London last year, that was just stupid."

Coach Brian McClennan admitted Rhinos' 36-26 victory was too close for comfort.

"Harlequins played very, very well," he said. "That was a tough match, we are ecstatic and very proud that we've come through.

"It was one hell of a Cup tie. We have got confidence that we can score tries, that's the beauty of the side.

"There's a lot of speed and we can generate opportunities very quickly. For the majority of the match they would have won the physical contest.

"They were grinding us down, but we are a dangerous side in that we can just break out and score.

"That's how we got away with the win."

McClennan hailed Peacock's energy and Sinfield's quick-thinking, but felt it was a team effort.

He said: "Jamie played 80 minutes and that was a great effort by a big man in the heat, one of many great efforts by all the players on the field.

"It was a big play by Kevin. We talked about it earlier in the week. We were going to save it for later on, but it was needed today!"

The coach added: "It was hot, in the second half we had a lack of possession, so you need all hands on board.

"I don't want to single anyone out, because when you've got a team full of steam coming at you, with plenty of possession and territory like Harlequins – who were a bigger side than us – you need all hands on deck to hang in there.

"We did and there was moments of brilliance by some of the quick-stepping guys in our team."