BAD BLOOD has long been the fuel that drives combat sports.

In the UFC, grudges have been the essence of its existence. Saturday, its latest will come full circle when top contender Rashad Evans finally will get his mitts on light-heavyweight champion Jon Jones at UFC 145 in Atlanta (10 p.m.).

While the UFC has its latest pay-per-view card scheduled for 12 bouts, it's safe to say they'll all be on the back burner behind this highly anticipated main event.

This fight perhaps has had the biggest lead-up to any in the history of the UFC light-heavyweight division, right up there with the great throwback battles Tito Ortiz had against Chuck Liddell and Ken Shamrock. Evans and Jones have added their names to the pantheon of UFC's most memorable matches - before even throwing a single punch.

"The light-heavyweight division has always been a special weight class in the UFC and the Jon Jones-Rashad Evans match could be the biggest fight at 205 pounds in years," said UFC president Dana White.

To fully understand what makes this fight so enthralling, you have to go back to 2009. The two then were actually training partners and friends, both plying their trade with trainer Greg Jackson at his camp in Albuquerque, N.M. But Evans left Jackson's camp for what he called a "fresh start" in Florida. It's been reported that as Jones grew from training partner to one of UFC's best in the light-heavyweight division, so did the strain on his relationship with Evans. Jones (15-1 UFC/MMA record) captured the crown after defeating Mauricio "Shogun" Rua at UFC 128 last March, becoming the youngest light-heavyweight champion at age 23.

"This fight has a tremendous back story with it having grown out of a friendship that went sour back when these two were teammates," Shamrock told UFC.com. Shamrock, the UFC's first light-heavyweight champion, was the second-longest titleholder (1997-99), only behind arch nemesis Ortiz, who took Shamrock's crown and held it from 2000-03. "The drama that's fueling this is incredible."

The bitterness between Jones and Evans came to a head inside the MGM Grand in Las Vegas on a night when both men were at a nightclub. It was reported that a squabble turned into pushing and shoving that had to be broken up by another MMA fighter at the club.

Call it prefight TNT.

"I have no regrets, I said what I had to say because it's how I felt at the time," Jones said of the incident, speaking to reporters via teleconference last Friday. "He knows where I am coming from and I don't think I crossed the line at all. We both have been looking forward to this fight for a long time and for whatever reason it's been put off. But it's here now and I'm done talking. I just want to get in there and do my thing."

It has been a lengthy wait for the fighters and fans alike. For Evans (12-1-1, UFC; 22-1-1 MMA), it's been climbing his way back to Jones after a hand injury - while watching other fighters in the division pull ahead of him. Evans was scheduled to fight top contender and Harrisburg native Phil Davis last August at UFC 133 inside the Wells Fargo Center, but Davis suffered a knee injury in training. Instead, the main event was against Ortiz, and Evans made quick work of him in front of a packed house.

"Whenever you compete, you always want to get a chance to fight for the belt - I mean, that is the ultimate goal," Evans said last Friday during a prefight teleconference. "Just having Jon promised to me really has been a gift and a curse, because that's [the fight] everybody kept talking about and the only fight I've been thinking about. I think that title being out there and the No. 1 contender title being open for discussion and not definitively mine became a weight that just got annoying after a while.

"[With those other fights] it just became, 'Let's just get this over with,' so I can fight for the belt I should have been fighting for a long time ago."

Contact Kerith Gabriel at gabrielk@phillynews.com