At 40, it's remarkable that four-division champion Juan Manuel Marquez can still make a claim as one of the sport's pound-for-pound elites.
Marquez (55-7-1, 40 KOs), who made his pro debut nearly 21 years ago as a junior featherweight, can move one fight closer to his goal in Saturday's welterweight title eliminator against Mike Alvarado at The Forum in Inglewood, California (HBO, 10:15 p.m. ET/PT).
A victory over Alvarado (34-2, 23 KOs) would put Marquez in position to fight for a fifth world title in as many weight classes, becoming the first Mexican-born fighter to do so. But he will need to get past a determined fighter in Alvarado to get there.
Here are five keys Marquez should consider entering Saturday's fight: