The UFC finishes its pay-per-view schedule for the year with a championship doubleheader as UFC 181 takes place Saturday at Las Vegas’ Mandalay Bay Events Center.

Welterweight titleholder Johny Hendricks (16-2 MMA, 11-2 UFC) and lightweight champ Anthony Pettis (17-2 MMA, 4-1 UFC) both look to defend their belts for the first time as they return from surgery-induced layoffs.

Eager to take the gold are two challengers that want to make the most of their second opportunity to fight for a UFC belt. Top 170-pound contender Robbie Lawler (24-10 MMA, 9-4 UFC) challenges Hendricks while former Strikeforce champ Gilbert Melendez (22-3 MMA, 1-1 UFC) goes for the title at 155 pounds.

For more on the numbers behind what will be the 300th event overall in UFC history, check out 65 pre-fight facts for UFC 181.

Main event

Hendricks returns to the octagon after a 265-day layoff, his longest break from competition dating back to his September 2007 debut.

Hendricks will compete in the first rematch of his career.

Hendricks’ 11 UFC welterweight victories are tied for the fifth most in divisional history behind Georges St-Pierre (19), Matt Hughes (16), Josh Koscheck (14) and Jon Fitch (13).

Hendricks’ past three fights have ended in a decision, the longest stretch of his professional career without a finish.

Hendricks’ five knockout victories in UFC welterweight competition are tied for the fifth most in divisional history behind Matt Brown (nine), Thiago Alves (seven), Anthony Johnson (six) and Hughes (six).

Hendricks has never been knocked down in his career.

Hendricks is one of four fighters in UFC history to record three knockout victories in less than one minute each. Vitor Belfort, Johnson, Mike Swick are the others. He accomplished the feat against Martin Kampmann (UFC 154), Fitch (UFC 141) and Amir Sadollah (UFC 101).

Hendricks’ 12-second knockout of Fitch at UFC 141 is the second fastest in UFC welterweight history. Duane Ludwig, who stopped Jonathan Goutlet in six seconds at UFC Fight Night 3, holds the record.

Hendricks lands 29.7 percent of his significant strikes in the clinch, the second largest margin among active welterweights behind Swick (40.9 percent).

Hendricks has completed 40 takedowns in UFC welterweight competition, the most among active fighters in the weight class and fourth most in divisional history.

Hendricks’ 12 takedowns landed against Carlos Condit at UFC 158 are tied for the fourth most ever landed in a single UFC fight.

Hendricks has been awarded six fight-night bonuses in his UFC career, tied for the second most of any welterweight in company history behind Chris Lytle (10).

Hendricks and Lawler combined for 308 significant strikes landed over the course of their five-round bout at UFC 171. That tally set a new record for a UFC championship fight, obliterating the previous total of 256, which was set by Condit and Nick Diaz at UFC 143.

Hendricks and Lawler attempted 728 significant strikes in their first meeting, the second most ever in single UFC bout behind Cole Miller and Nam Phan, who attempted 788 significant strikes at UFC on FOX 4.

Hendricks’ 158 significant strikes landed against Lawler stand as the most ever for a UFC title bout. Lawler, who landed 150 significant strikes, tied the fourth-highest tally ever for a championship fight.

Lawler is 5-1 since he returned to the UFC for a second stint in February 2013. The lone defeat during that stretch came to Hendricks.

Lawler’s seven knockdowns landed in UFC welterweight competition are tied for the fifth most in divisional history behind Alves (10), Johnson (eight), St-Pierre (eight) and Jake Ellenberger (eight).

Lawler has a 14:1 knockdown ratio in UFC/PRIDE/Strikeforce/EliteXC competition.

Lawler has completed 80 percent of his takedown attempts (16 of 20) in UFC competition, the highest accuracy rate in UFC history.

Co-main event

Pettis returns to the octagon after a 462-day layoff, his longest break from competition dating back to his January 2007 debut.

Pettis’ four-fight UFC winning streak is the fifth longest active streak in the lightweight division behind Khabib Nurmagomedov (six), Myles Jury (six), Donald Cerrone (five) and T.J. Grant (five).

Pettis has earned his past three UFC victories by first-round stoppage.

Pettis has earned three knockouts in UFC/WEC competition stemming from a roundhouse kick to the head or body, more than any other fighter. Adding Strikeforce and PRIDE competition, the only fighter with more such victories is Mirko Filipovic with seven such one-kick finishes.

Pettis is one of two fighters in UFC history to earn two consecutive knockouts stemming from a kick to the head or body. Belfort is the other to accomplish the feat.

Pettis absorbs just 1.32 significant strikes per minute, the third lowest rate in UFC lightweight history behind Jury (1.22) and Matt Serra (1.24).

Pettis has never been finished in his career.

Melendez will challenge for the UFC lightweight championship for the second time in three octagon appearances

Melendez reigned as Strikeforce champion for 1,135 days, the longest title run of any lightweight champion in UFC/WEC/Strikeforce combined history.

Melendez’s 11 victories under the now-defunct Strikeforce banner stand as the most in company history.

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

Melendez has never been finished in his career.

Remaining main card

Travis Browne (16-2-1 MMA, 7-2-1 UFC) has earned 14 of his 16 career victories by stoppage. “Hapa” has finished his opponent in all but one of his UFC victories.

Browne has earned five first-round knockout victories in UFC heavyweight competition. Only Cain Velasquez, Andrei Arlovski and Roy Nelson, who have six first-round finishes, have recorded more.

Browne is the only fighter in UFC history to earn two knockout victories stemming from standing elbow strikes. He used the technique to finish Josh Barnett at UFC 168 and Gabriel Gonzaga at the TUF 17 Finale.

Browne has been awarded five fight-night bonuses in his UFC career, tied for the second most of any heavyweight in company history behind Nelson (six).

Browne, who stands at 6-7, is the second tallest fighter on the UFC roster (Struve).

Brendan Schaub (10-4 MMA, 6-4 UFC) has earned four of his six UFC victories by stoppage. He’s suffered three of his four career losses by first-round knockout.

Schaub is 2-3 in his past five UFC appearances.

Schaub is the only fighter in UFC heavyweight history to earn a D’Arce choke submission. He accomplished the feat against Matt Mitrione at UFC 165.

Schaub has completed 47.8 percent of his takedown attempts in UFC heavyweight competition, the highest accuracy rate among active fighters in the weight class.

Schaub lands 84.7 percent of significant strikes to his opponent’s head, the second largest proportion of head strikes in UFC heavyweight history behind Mark Hunt (87.4 percent).

Todd Duffee (8-2 MMA, 2-2 UFC) returns to the octagon after a 707-day layoff, his longest break from competition dating back to his February 2007 debut.

Duffee has earned all of his career victories by knockout.

Duffee’s seven-second knockout of Tim Hague at UFC 102 stands as the fastest knockout in heavyweight history and is tied for the third fastest knockout overall in UFC history.

Anthony Hamilton’s (13-3 MMA, 1-1 UFC) knockout of Ruan Potts at UFC 177 stemmed from multiple body punches on the ground. It was just the second finish of its kind in UFC history along with Antonio Rogerio Nogueira’s stoppage of Tito Ortiz at UFC 140.

Hamilton landed 49 significant body strikes in Round 2 against Potts are a single-round UFC record.

Tony Ferguson (16-3 MMA, 6-1 UFC) has earned four of his six UFC victories by first-round stoppage.

Ferguson is one of 12 fighters in UFC history to earn a D’Arce/brabo choke submission win. He accomplished the feat against Mike Rio at UFC 166. The finish at the 1:52 mark of Round 1 was the quickest of its kind in UFC history.

Ferguson lands 99 percent of his significant strikes on the feet, the third largest standing strike proportion in UFC lightweight history.

Abel Trujillo (12-5 MMA, 3-1 UFC) has earned all three of his UFC victories by knockout.

Trujillo was awarded $125,000 for “Fight of the Night” and “Knockout of the Night” honors for his second-round knockout of Jamie Varner at UFC 169 in February.

Trujillo was taken down a UFC record 21 times in his unanimous decision loss to Nurmagomedov at UFC 160.

Preliminary card

Urijah Faber (31-7 MMA, 7-3 UFC), 35, is the oldest of the 22 fighters scheduled to compete at the event.

Faber is undefeated in non-title bouts throughout his professional career.

Faber is one of four fighters in UFC history to go 0-3 in UFC championship fights. Other fighters with the unflattering feat are Pedro Rizzo, Chael Sonnen and Kenny Florian.

Faber will compete in his 11th UFC bantamweight contest, the most in divisional history. His total fight time of 2:12:30 is the most in 135-pound history.

Faber’s seven victories in UFC bantamweight competition are tied with four other fighters for the most in divisional history.

Faber’s 13 stoppage victories in UFC/WEC competition are tied with Belfort, Hughes and Nate Diaz for the second most in the combined history of the two organizations behind Anderson Silva (14).

Faber’s five stoppage victories in UFC bantamweight competition are tied with T.J. Dillashaw for the most finishes in divisional history. His six stoppage wins in UFC/WEC bantamweight history are also tied for the most in the combined history of the weight class.

Faber’s 12 submission victories in UFC/WEC/Strikeforce/PRIDE competition are tied with Kazushi Sakuraba for the second most of any fighter in the combined history of the four organizations behind Antonio Rodrigo Nogueira (13).

Faber’s 12 submission victories in UFC/WEC competition are tied with Royce Gracie for the most in the combined history of the two organizations. In terms of his overall career, Faber has 18 submission victories to his name, with 16 of them coming by rear-naked or guillotine chokes.

Faber’s five submission victories in UFC bantamweight competition are the most in divisional history. He also holds the record for most submissions in UFC/WEC bantamweight history with six.

Faber has completed 18 takedowns in UFC bantamweight competition, the most in divisional history.

Faber’s 11 fight-night bonuses under the Zuffa banner are tied for fourth most in UFC/WEC history behind Cerrone (15), Joe Lauzon (13), and Silva (13). He is tied with Lauzon for “Submission of the Night” honors six bonuses for impressive tap-outs.

Francisco Rivera (10-3 MMA, 3-2 UFC) has suffered just one defeat in his past seven bouts.

Rivera’s four knockdowns landed in UFC bantamweight competition are tied for the third most in divisional history behind Michael McDonald (five) and Dillashaw (five).

Rivera lands 4.15 significant strikes per minute, the fourth highest rate in UFC/WEC bantamweight history.

Rivera’s significant strike defense rate of 69.9 percent in UFC bantamweight competition is the third highest in divisional history behind Vaughan Lee (71.5 percent) and Raphael Assuncao (70.8 percent).

Josh Samman (10-2 MMA, 1-0 UFC) returns to the octagon after a 602-day layoff, his longest break from competition dating back to his April 2007 debut.

Corey Anderson’s (4-0 MMA, 1-0 UFC) 61-second knockout of Matt Van Buren at the TUF 19 Finale marked the fastest finish ever to a finale of “The Ultimate Fighter” reality show.

Justin Jones (3-0 MMA, 0-0 UFC) makes his UFC debut just 321 days after his first professional fight.

Raquel Pennington (4-4 MMA, 1-1 UFC) has just one victory in her past four fights.

Sergio Pettis (11-1 MMA, 2-1 UFC), 21, is the youngest of the 22 fighters scheduled to compete at the event. He’s also the youngest active fighter in the UFC bantamweight division.

Pettis will compete on the same card as his older brother, Anthony, for the first time in his professional career.

For more on UFC 181, check out the UFC Rumors section of the site.

FightMetric research analyst and live statistics producer Michael Carroll contributed to this story. Follow him on Twitter @MJCflipdascript.