Winning a UFC championship once is an incredible feat for an MMA fighter. Winning a championship only to lose it and win it back again? A nearly impossible task.

Yet oddly, one half of the UFC 166 main event has already accomplished that task, and the other half looks to follow suit.

Two-time UFC heavyweight champion Cain Velasquez once again meets a familiar foe inside the octagon when he puts his belt on the line against Junior dos Santos this Saturday from Houston’s Toyota Center (pay-per-view, 10 p.m. ET).

Including UFC 166, Velasquez (12-1 MMA, 10-1 UFC) and dos Santos (16-2 MMA, 10-1 UFC) have competed on the same card in five consecutive bouts, which makes it seems more and more likely their names are destined to be intertwined with each other forever.

The outcome of Saturday’s fight could likely determine who is the best heavyweight fighter of this era, which only heightens the stakes for what will be the 13th trilogy to conclude under the UFC banner.

While all eyes are on the heavyweights going into Saturday’s pay-per-view event, UFC 166 is loaded from top-to-bottom, and with the help of FightMetric, it’s time to take a closer look at the numbers for Velasquez, dos Santos and everyone else scheduled to compete on the card.

MAIN EVENT

Velasquez and dos Santos each own 10 UFC victories; however, they have no common opponents.

Velasquez is one of only five fighters in UFC history to win multiple championships in a single weight class (Randy Couture, Georges St-Pierre, Matt Hughes and Tim Sylvia).

Velasquez’s eight UFC knockout victories are the most for any fighter in heavyweight history.

Velasquez is the only fighter in UFC history to land 100 or more significant strikes and 10 or more takedowns in the same fight.

Velasquez has landed 983 total strikes in his UFC career, the most of any active UFC heavyweight.

Velasquez’s striking differential rate of 4.91 is the highest of any fighter in UFC history.

Velasquez has successfully completed 27 takedowns in his UFC career, the most of any heavyweight in history.

Velasquez lands 6.5 significant strikes per minute of fighting, the highest rate of any fighter in UFC history.

Velasquez is 2-0 in his career when facing an opponent for the second time. He has never competed in a trilogy bout.

Dos Santos’ 11 knockdowns landed in UFC competition are the most in heavyweight history.

Dos Santos’ seven UFC knockout victories are tied for the second most for any fighter in heavyweight history.

Dos Santos has landed 574 significant strikes in his UFC career, the most of any active heavyweight.

Dos Santos’ striking differential rate of 2.78 is the second highest in heavyweight history. “Cigano” lands 5.46 strikes per minute, the third highest rate of any fighter in UFC history.

CO-MAIN EVENT

Daniel Cormier (12-0 MMA, 1-0 UFC) has never been taken down in his 12-fight MMA career.

Cormier’s four knockout victories under the Strikeforce banner were the second most in the organization’s history.

Roy Nelson (19-8 MMA, 6-4 UFC) has earned all six of his UFC victories by knockout, five in the first round. Nelson’s six UFC knockout victories are the fourth most in heavyweight history.

Nelson is the only fighter in UFC heavyweight history to lose four fights by decision.

Nelson has absorbed 437 significant strikes in his UFC career without being finished, a heavyweight record.

Nelson’s four “Knockout of the Night” bonuses are tied with Vitor Belfort for the second most in history. Former middleweight champ Anderson Silva leads the category with seven knockout bonuses.

REMAINING MAIN CARD

Diego Sanchez (24-5 MMA, 13-5 UFC) has earned his past five victories by decision and has not finished an opponent since Luigi Fioravanti at The Ultimate Fighter 17 Finale in June 2008.

Sanchez’s 3:52:57 of total fight time over his 18-fight UFC career ranks ninth in organizational history.

Sanchez’s five “Fight of the Night” bonuses are the fourth most in UFC history.

Sanchez is one of two fighters in UFC history (Thiago Alves) to earn two victories by flying-knee knockout.

Sanchez has attempted a higher number of significant strikes than his opponent in 12 of his 13 UFC wins.

Sanchez’s 127 takedown attempts are the third most in UFC history behind Clay Guida and Frankie Edgar.

Gilbert Melendez‘s (21-3 MMA, 0-1 UFC) 11 victories under the now-defunct Strikeforce banner were the most in history.

Melendez’s 749 significant strikes landed during his Strikeforce career were the most in organizational history.

Opponents Gabriel Gonzaga (15-7 MMA, 10-6 UFC) and Shawn Jordan (15-4 MMA, 3-1 UFC) have earned 29 of 30 combined career victories by knockout or submission.

Gonzaga’s 17-second knockout of Dave Herman at UFC 162 tied the record for the third fastest knockout in UFC heavyweight history.

Gonzaga will compete in his 17th UFC heavyweight bout, the third most in organizational history behind Cheick Kongo (18) and Frank Mir (22).

Gonzaga owns 10 career knockout or submission victories in the UFC, which is the second most of any heavyweight in history behind Mir (11).

Gonzaga’s 10 submission attempts in UFC competition are the third most in heavyweight history behind Stefan Struve (19) and Mir (20).

Gonzaga’s average fight time of 5:22 is the shortest among active UFC heavyweights.

Gonzaga’s 48.7 percent takedown accuracy is the highest among active UFC heavyweights.

USA TODAY Sports/MMAjunkie.com No. 9 ranked flyweight Darrell Montague (13-2 MMA, 0-0 UFC) makes his organizational debut with 10 victories in his past 11 fights.

PRELIMINARY CARD

Tim Boetsch‘s (16-6 MMA, 7-5 UFC) average fight time of 13:51 is the fourth longest in UFC middleweight history.

Boetsch’s 52.94 percent significant strike accuracy is the third highest in UFC middleweight history.

C.B. Dollaway‘s (13-4 MMA, 7-4 UFC) Peruvian necktie submission of Jesse Taylor at UFC Fight Night 14 is the only submission of its kind in UFC history.

Opponents Hector Lombard (32-4-1 MMA, 1-2 UFC) and Nate Marquardt (32-12-2 MMA, 10-5 UFC) share 84 fights of professional MMA experience, the most of any matchup on the card.

Lombard is set to compete in the welterweight division for the first time in his 38-fight professional career.

Marquardt’s 73 percent takedown accuracy in middleweight competition is the highest rate in the division’s history and second highest rate all-time behind Georges St-Pierre (75 percent). His 27 takedowns landed as a UFC middleweight are tied for the third most in the division’s history.

Marquardt’s eight knockdowns landed at middleweight are tied for the second most in the division’s history. Anderson Silva leads the category with 12.

Former Strikeforce women’s bantamweight champion Sarah Kaufman (16-2 MMA, 0-0 UFC) makes her debut against three-fight Bellator MMA veteran Jessica Eye (10-1 MMA, 0-0 UFC).

Kaufman’s 681 significant strikes landed in her Strikeforce career were the second most in history behind Melendez.

Kaufman’s 164 significant strikes landed against Takayo Hashi at Strikeforce Challengers 6 is the promotion’s single-fight record.

Kaufman’s 84.5 percent takedown defense rate was the second highest in Strikeforce history. Tarec Saffiedine led the category with an 85.4 percent average.

Opponents George Sotiropoulos (14-5 MMA, 7-3 UFC) and K.J. Noons (11-7 MMA, 0-1 UFC) both enter the event on career-worst three-fight losing streaks.

T.J. Waldburger‘s (16-7 MMA, 4-2 UFC) 6.36 submission attempts per 15 minutes of fighting is the highest rate of any fighter in UFC welterweight history. Waldburger has submitted his opponent in 13 of his 16 professional victories.

Tony Ferguson (13-3 MMA, 3-1 UFC) competes for the first time since May 5, 2012 – a span of 532 days and the longest layoff of his 16-fight professional career.

Andre Fili (12-1 MMA, 0-0 UFC) makes his UFC debut on 12 days’ notice after stepping in as an injury replacement for Charles Oliveira.

For more on UFC 166, stay tuned to the UFC Rumors section of the site.

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