BJ Penn might as well be a dead man walking on Saturday night.
MacDonald is the surging young star with all of the potential in the world, while Penn is a dried up version of a past pound-for-pound great.
Fans shouldn't be faulted for their assessment of Penn. The former UFC welterweight and lightweight champ brought it on himself.
Outside of UFC light heavyweight champ Jon Jones, there has never been a more naturally gifted athlete in MMA than Penn, who won the World Jiu-Jitsu Championships with only three years training.
As the saying goes, "hard work beats talent when talent doesn't work hard."
Penn's work ethic has been questioned throughout his entire career. Fans would often ponder the same questions leading up to big fights.
Is BJ motivated enough? Has he trained and dieted the right way?
At the top of his game, Penn was considered the best pound-for-pound fighter in the world, but now, fans see a first round fighter who tends to fade when faced with adversity.
Unfortunately, it took Penn losing to Nick Diaz in October 2011 to finally see what the rest of the world was seeing.
There weren't any excuses left to give. Penn took a physical and mental beating, and his face showed it for the first time in his career.
After the fight, Penn announced his retirement from MMA, but the competitive part of him wouldn't let him walk away.
Now, he is set to face a young lion in MacDonald, and for the first time in his career, Penn is being looked at as a stepping stone.
During the media conference call for UFC on Fox 5, the former champ poured his heart out to media and fans:
"I watch all these interviews and all these people talking, and no one says my name when they talk about the greatest fighters any more, and I really don't like that. It really bothers me, and I know it's my fault. I know I'm the reason why people don't talk about me when they talk about GSP or Anderson Silva.
My name was always in the mix. It's never in the mix any more, and I told Dana [White] I've got a big problem with that, and that was actually part of my motivation to come back strong and do a good fight on December 8. Everything is current, and I don't want to be known as, 'Oh, he was good back in the day.' I want to be known as the best."
A BJ Penn with his back against the wall is a very dangerous fighter.
The problem has always been Penn's work ethic, not his overall skill. According to trainers and sparring partners, Penn is more motivated than he's ever been. A quick look at his physique shows the seriousness of this fight.
People tend to forget he took the first round in both of his welterweight bouts with top contenders Diaz and Jon Fitch.
What if he could sustain the same effort throughout an entire fight?
Longtime fans remember the first time Penn fought Matt Hughes for the welterweight title in January 2004. The mere idea of a lightweight moving up and defeating one of the greatest welterweights in the history of the sport was unheard of.
Yet, Penn proved the naysayers wrong by submitting Hughes in the first round and winning the UFC title.
MacDonald is a completely different fighter than Hughes, and times have changed. Still, it's ludicrous to completely write Penn off in this fight.
If fans truly are about to witness the best BJ Penn ever on Saturday night, there are going to be a lot of wrong people on Sunday morning.