Carl Froch knocked out George Groves to retain his IBF and WBA super-middleweight titles on Saturday night with an eighth-round right-hand punch he said was the most satisfying of his career.

"That was the best punch of my life," Froch said. "You define a good punch from what it means, and what that meant was the whole George Groves saga and the history of the fight came to an end.

"I just threw it, I didn't really try to knock him out. I didn't load up, I just threw the punch and just landed it lovely. It was just a lovely pear of a shot and it closed the show."

The 36-year-old Froch had beaten Groves with a controversial ninth-round stoppage in November, and the London challenger, 10 years Froch's junior, had claimed in the build-up to Saturday's fight - before a crowd of 80,000 - that he would knock out the champion.

"I've had George Groves in the back of my ear hole for the last year because he was in my ear for the [Mikkel] Kessler fight in May 2013," the Nottingham boxer said. "It's now May 2014. I've boxed Groves twice in a year and I've just not heard the end of it.

"I said my legacy was at stake and it was, because unfortunately in boxing people remember you for your last fight. My career would have been over - I would have retired if I had lost."

After the fight, Froch offered Groves some words of consolation.

"I told him not to go home and be too down and out or go on a downward spiral because you're a great fighter - you were in that fight up until that point," Froch explained. "I said that from the start - he's a good fighter, he's got quick hands, he's skilful."

Groves, for his part, was magnanimous in defeat.

"Carl Froch is a strong, seasoned world champion and there's no quit in him," Groves said. "Fair play to Carl, he got the job done and was the better man on the night.

"I'm still 26 years old. I didn't get the result I wanted but I was boxing well and I'm sure I'm going to have a long boxing career ahead of me."