It's fair to say Tony Bellew and David Haye weren't the best of friends in the world of boxing.The two clashed a series of times in the media as they negotiated two fights, both of which were won by Bellew.The Evertonian shocked the boxing world last year as he upset the odds to beat Haye, who limped through most of the fight after rupturing his Achilles tendon and threw the towel in in the 11th round.And in the rematch last month, Bellew comfortably brushed off Haye within five rounds in a fight that turned out to be his last, with the veteran fighter announcing his retirement on Tuesday.Though he wasn't everyone's cup of tea, Haye still had a respectable career which peaked with his heavyweight fight against Wladimir Klitschko, which he ultimately lost.His first retirement, that he later backtracked on, certainly didn't win many fans either, with some still wondering whether another big payday would draw him out of retirement for a second time.Though Haye and Bellew were always quick to exchange words in the build-up to their bouts, they were quick to embrace afterwards each time, and naturally, Bellew has come out to have his say on arguably his biggest rival in the sport.Writing on his Twitter account, Bellew wrote: "Nothing but respect and admiration for you.."You’ve had a career that any fighter would be immensely proud of.

"Thank you for giving me the opportunity to fight yourself the first time around!

"It changed mine & my families life forever so I’ll always be indebted to you. #Respect👊"

Fair play, Tony, and the boxing world also appreciated what he had to say.

The two definitely didn't see eye-to-eye when they were opponents, but Bellew has had the class to come out and admit that the opportunity that Haye gave him has helped him to get to where he is now.

Haye can look back on a good 16-year career in the sport, and none of us will forget that press conference brawl with Chisora. That's if he is actually retiring this time...