Anger is a great motivator.
And the thread of dislike between UFC 145 headliners Jon "Bones" Jones and "Suga" Rashad Evans runs long and nasty.
The training-partners-turned-foes have held back little in outlining their disdain for one another in the buildup to Saturday's light-heavyweight title fight in Atlanta.
Former champ Chuck Liddell knows a thing or two about fighting mad.
"Everyone is different but, I think, for most fighters getting into the Octagon with someone they don't like is a great motivation in training," says Liddell, who, like Jones, was a seemingly unbeatable 205-pound champ from 2005 to '07.
"Every time you are tired or holding a little back, you think about losing to this guy. You can't stand and it helps you give 100%. That's how I was with Tito (Ortiz). I couldn't stand the idea of losing to him and so I trained harder."
The similarities between Jones/Evans and Liddell/Ortiz run deeper.
Liddell and Ortiz also trained together. While both Jones and Evans were trained by Greg Jackson, Liddell and Ortiz were both managed by Dana White before he became UFC president.
Liddell says whoever was the dominant fighter during their training together -- Evans has always said it was him -- has a mental advantage going in.
"I'd love to know who really got the best of it when (Jones and Evans) trained together," says Liddell, who retired after losing to Rich "Ace" Franklin by knockout at Vancouver's UFC 115 in June 2010.
"You get a feeling for someone when you spar with them. That's why I was so confident against Tito. I'd beat him up standing, wrestling and at BJJ (Brazilian jiu-jitsu) when we trained together years before our fights and I knew I was in his head because of that."
Evans has gone so far as to say when Jones first showed up at the Jackson gym, he had to hand-hold the newbie through everything from fighting to learning how to dress.
"Listening to Rashad, he feels he's in Jon's head a little," says Liddell. "He sounds very confident and I think that's based on experiences in the gym."
Jones says the kid he fought in the gym is not the man Evans will face in Atlanta.
Liddell says the key to an Evans victory will be to get on the young champ early.
"I'm glad (Evans) is confident, because that's something you have to have against Jones. If you don't go after Jon, you are in for a bad night," says Liddell.
UFC 145 includes three Canadians on the main card:
B.C's Rory MacDonald will face Che Mills; London's Mark Hominick will face Eddie Yagin and Toronto's Mark Bocek will take on John Alessio.
Chris Clemente of Chatham, Ont., will take on Keith Wisniewski, and Quebec's John Makdessi will face Anthony Njokuani in undercard action.
UFC 145 is available on pay-per-view