David Haye has vowed not to make "the same mistake twice" in his rematch against Tony Bellew, which he describes as his "last chance".
Haye was beaten in the 11th round of their first meeting after suffering an ankle injury but concedes that he must make tactical improvements before meeting Bellew again on December 17, live on Sky Sports Box Office.
"I need to raise my game. If I show up in the same condition, if I turn up with the same tactics and the same mind-set then he's correct - he could walk away with the victory," Haye told Sky Sports News. "But I'm not a stupid fighter.
"Maybe tactically, I went about it incorrectly. I've made mistakes in the past and learned from them.
"I don't believe I was complacent. I trained very, very hard. It wasn't down to not putting in the work. As you saw, I was swinging until the bitter end and if I wasn't [in good cardiovascular condition] I wouldn't have been able to do what I did.
"I reviewed the fight and I know what happened - I understand his strengths, and I understand my strengths and weaknesses. He showed me something that I didn't believe he had.
"By the time I get into the ring [for the rematch] I'll be 37 but I haven't won multiple world titles in multiple weight classes by making the same mistake twice."
Haye has spent the past few months recuperating the ankle injury that he sustained in the first fight but insisted that he is fully healed: "I'm in a good physical place. My recovery from a ruptured Achilles has gone fantastically well. I've spent hours every day working behind the scenes so when I step into the ring, there will be no excuses. Nothing will break down."
The former cruiserweight and heavyweight world champion has split with coach Shane McGuigan, who threw in the towel to end the first fight against Bellew. Haye believes that linking up with Cuba's Ismael Salas will re-establish his fundamental abilities.
Asked about Salas, Haye said: "He's trained 19 world champions, he was the Cuban Olympic coach and coached [amateur legend] Felix Savon from his very first jab.
"He understands my skill-set, he understands my age - he's studied the fight and has put together a game-plan. We've gone back to basics. We're working on things I already knew, but maybe I had forgotten. When you have big gaps between fights, you don't forget boxing, but you need to scrub up on the basics. The basics, recently, have looked shady."
Haye insisted that the difficulties he experienced in March's defeat to Bellew will strengthen him ahead of their second fight.
"The first time around, I wasn't mentally anticipating a tough battle but I found myself in one," he said. "This time, I know it can happen. I've tasted his punches, I've seen him take my punches. He's a serious contender so I need to be on my A-game mentally and spiritually. I didn't believe I needed that prior to the first fight.
"I know this is my last chance, I'll never get another chance after this. Whatever heart and determination you saw in the last fight, you'll get the same or more this time.
"If I can't knock Tony Bellew out, that's it for me. If I can't knock him out then I'm not the fighter that I once was, and I'm not the fighter that I believe I am."
Tony Bellew vs David Haye II is live on Sky Sports Box Office from The O2 in London on Sunday, December 17.