Record: 13-1 overall, 4-1 in the UFC
Key Wins: Mike Pyle (UFC 133), Nate Diaz (UFC 129), Che Mills (UFC 145)
Key Losses: Carlos Condit (UFC 115)
How he got here: At just 22 years old, Rory MacDonald has already been fighting for nearly six years professionally. "Ares" fought the King of the Cage Canada circuit, working his way up to and winning the promotion's lightweight title when he was 19 years old. After winning the title, he fought for the overall King of the Cage belt and won that as well the next November.
He would never defend his titles, simply outgrowing the 155 pound division and moving to welterweight. After one more victory on the local circuit, he made his UFC debut last January, defeating Mike Guymon with a first round submission.
MacDonald was all over former WEC champion Carlos Condit for two rounds in his second fight with the promotion before fading in the third and getting stopped with just seven seconds left in the round. After joining the Tristar Gym, he would rebound at UFC 129 against Nate Diaz, destroying the Stockton fighter with slams, wrestling, and ground and pound over the course of three rounds to get back on track in the division.
In his last two fight, MacDonald crushed Mike Pyle with a first round knockout via ground and pound and steamrolled Che Mills via second round TKO utilizing the same method.
After the fight was initially delayed due to a cut MacDonald suffered, the bout is going ahead as scheduled on Saturday night.
How he gets it done: MacDonald is so talented, young and well-rounded already at this point in his career. The key to victory would be to neutralize what Penn does best and punish him with his physical gifts.
MacDonald has some pretty nice striking skills, but there's no point standing in the pocket and trading with the Penn when he can try to work for takedowns and beat "The Prodigy" up on the canvas just like he did in his last two fights. I fully expect the Canadian to close the distance either with a shot or by simply clinching and then working extremely diligently to take Penn for a ride. .
It won't be easy because Penn's takedown defense is legendary, but it can and has been done by fighters who wore down the Hawaiian first in the clinch or gave an opportunity for fatigue to set in. If Penn slows down even the slightest bit, MacDonald can overwhelm him.
Record: 16-8-2 overall, 13-7-2 in the UFC
Key Wins: Matt Hughes 2x (UFC 123, UFC 46), Diego Sanchez (UFC 107), Kenny Florian (UFC 101)
Key Losses: Nick Diaz (UFC 137), Frankie Edgar 2x (UFC 118, UFC 113), Georges St. Pierre 2x (UFC 94, UFC 58)
How he got here: B.J. Penn was a legend before he ever even entered the UFC, having been the first American Brazilian jiu-jitsu black belt to win the gold medal in the World Jiu-Jitsu championships in Rio de Janeiro, Brazil. Penn shocked the world when he blasted them top ranked lightweight Caol Uno in 11 seconds at UFC 34 but would come up short against champion Jens Pulver just two months later.
When Pulver relinquished the title to compete overseas, Penn fought Uno in a rematch to a draw that was so lukewarm that the UFC eliminated the entire lightweight division. One year later, upon his return to the UFC, he was awarded a welterweight title shot against then considered unbeatable champion Matt Hughes but "The Prodigy" took Hughes' back and choked him out in the first round to win the UFC title.
Instead of defending his belt, the Hawaiian left the UFC and his weight ballooned, even fighting future UFC champion Lyoto Machida at heavyweight. When he returned, he lost a hotly contested decision to Georges St. Pierre in a number one contender match but was granted the title shot when GSP couldn't make the date due to an injury.
This time around, Penn would get worn down by Hughes and an exhausted "Prodigy" would fade under Hughes' attack late in the third round. The Hawaiian took a year off, filmed season five of The Ultimate Fighter as a coach against Jens Pulver and then avenged his loss to "Little Evil" on the finale.
The newly motivated B.J. Penn would win the vacant UFC lightweight championship against Joe Stevenson and would defend it three times to soar up the pound-for-pound rankings. He would lose a welterweight title shot to Georges St. Pierre in the process and then would also lose consecutive decisions to current champion Frankie Edgar to surrender his lightweight title last year. Since then, Penn has moved to welterweight where he destroyed Hughes in a trilogy match and drew with consensus number two welterweight Jon Fitch early last year.
He was hoping to get back in the title picture against Nick Diaz, but after a strong first round, he was battered on the feet by the Stockton slugger and suffered such a disheartening loss that he retired in the cage post-fight. After nearly a year away from the cage, he returned to face rising welterweight star Rory MacDonald.
How he gets it done: B.J. Penn is an incredible Brazilian jiu-jitsu black belt and his boxing is very crisp. Utilizing that boxing is the key to victory for Penn against MacDonald.
MacDonald is a well-rounded fighter, but his pure stand-up on the feet is probably his biggest weakness at the moment. Penn needs to capitalize on that if he wants to hurt MacDonald. By keeping the fight standing, he can utilize his tremendous ability to counterstrike against "Ares."
Penn's counter-punching is incredible. He's very good at hitting opponents with shots they can't see coming, especially when he's not tired. If MacDonald wades in trying to knock his head off, Penn will be licking his chops with his left hook counter or even full combinations.
Staying on his feet will be vital for Penn. He's got tremendous takedown defense and a sense of balance. He's got to stuff every takedown attempt from MacDonald and then make him pay with punches and knees for his efforts.
MacDonald has been hurt on the feet before and Penn has the technique and power to make it happen again.
Fight X-Factor: The biggest X-Factor for this fight has to be the "new and improved" B.J. Penn. We all know that a motivated B.J. Penn is one of the scariest fighters in the world, we've seen him destroy Matt Hughes, leave a trail of bodies in the lightweight division and hold his own against the best welterweights, but we've also seen a sloppy-looking Penn get beat on by Nick Diaz in his last fight.
Penn hooked up with his old conditioning coach who got him in tremendous shape for the Jens Pulver rematch as well as the Joe Stevenson and Sean Sherk fights, three of his best performances in the Octagon. If there's any version of B.J. Penn that could beat Rory MacDonald, it's that one.
If Penn doesn't gas over three rounds, he's got a shot. A good one.
Bottom Line: This fight could be a potential changing of the guard. Penn is a living legend, a former two-divisional champion at lightweight and welterweight. It would be quite a feather in MacDonald's cap if he were to put him down. That being said, "The Prodigy" is not going down without a fight. Particularly in the first round, this bout has potential to go any which way. Penn could be in the best shape of his life and shock the world by tooling MacDonald or perhaps he could only do it for one round before fading. Hell, MacDonald could just beat up an older Penn for three rounds and force him into retirement again. There are so many possibilities and that's what makes this fight a "can't miss" opportunity for the fans.
Who will come out on top at UFC on Fox 5? Tell us your predictions in the comments below!