James DeGale and Nathan Cleverly have abandoned plans to spar each other again - because it was getting too competitive.
The Frank Warren fighters shared more than 30 rounds in April ahead of massive fights on May 21 at London's O2 Arena.
But a further week of sparring has been called off with both boxers deciding discretion, as the old saying goes, was the better part of valour.
"At the moment, James is a dangerous animal," said Cleverly, who takes on Jurgen Braehmer in a WBO light-heavyweight title showdown.
"We just couldn't risk any more sparring because we didn't want to take the edge off before our fights on May 21.
"It's the hardest sparring I've ever had, and remember, I sparred with Joe Calzaghe and Enzo Maccarinelli when they were both world champions."
DeGale, who features in a British and Commonwealth super-middleweight match up against Groves, echoed those sentiments, saying: "Nathan is definitely Britain's next world champion and I can't ever remember having harder sessions.
"Nathan just never stops throwing punches. He was the perfect preparation for Groves because I had to work a lot harder in sparring than I'll have to against Ugly Kid."
DeGale's trainer Jim McDonnell oversaw much of the sparring.
And he ranks among the best he has ever seen.
"I would have gladly paid to go and watch this in an arena," he said.
"In James and Nathan you have got two of the best young fighters in the country right now, and believe me, there was fireworks when they sparred.
"There were times when it was better than some world title fights that I have seen, it really was that good.
"Both lads are good friends and have a lot of respect for each other, and before sparring started they would be chatting away and having a laugh.
"But as soon as that first bell went, they would be in there throwing leather like there was no tomorrow.
"When these boys get in the ring all that respect goes out of the window, and they are at each other's throats.
"I'd have loved to have seen another week of sparring, but I want James to save his best for George Groves rather than waste it on Nathan Cleverly."
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