Mathubela will give everything he's got Saturday when he takes on Donaire in a super bantamweight title unification bout at the Home Depot Center in Carson, Calif.
That's how it is when guys fight Donaire, who is tied for sixth with heavyweight champion Wladimir Klitschko in the Yahoo! Sports rankings. Every fight is the fight of their lives because of how talented Donaire is.
Mathubela is plenty good himself, and holds the International Boxing Federation version of the 122-pound title. He's also a Manute Bol-like figure at super bantamweight, standing at 5 feet 10 1/2 inches and towering over most opponents by six or seven inches.
This fight, though, brings added pressure on Donaire, who hasn't had a knockout since the second-round knockout of Fernando Montiel 15 months ago that vaulted him into prominence.
Donaire has subsequently beaten Omar Narvaez and Wilfredo Vazquez Jr., but he hasn't looked particularly super in either one of them.
And while the name of the game is winning – Donaire is now 28-1 with 18 knockouts – more is expected when you're as good as Donaire.
Donaire's manager, Cameron Dunkin, is one of the shrewdest talent evaluators in the business.
He's raved for years about Donaire, and not even Donaire's less-than-stellar recent performances quelled Dunkin's enthusiasm.
"Nonito's a great fighter and maybe the best pound-for-pound fighter in the world," Dunkin said. "I just think he is that, and he grows in weight. He just moved to 122 pounds and you see how he's doing there. He just keeps winning and now he is taking time to work on his body as he moves to the higher weights. It's going to be terrific. Five, six, seven titles, who knows, when this all comes to an end."
It's time, though, for Donaire to separate himself from the pack. He's cruised on the brilliant performance against Montiel long enough. Narvaez took most of the criticism after their Oct. 22 bout in New York for not being willing to engage. And Donaire was unable to take out Vazquez despite controlling long stretches of it.
None of that is to belittle Donaire. It's just that he's so good, more is expected of him.
Donaire knows it. He knows that once opponents get the sense they can't beat him, they look for the next best thing, which is to survive and go the distance.
For all his brash pre-fight talk, Vazquez was in survival mode in the second half of their Feb. 4 bout in San Antonio.
Mathubela will, undoubtedly, create problems for Donaire with his height and his range. He's the same height as Mike Tyson and he's a literal giant in the super bantamweight class.
But Mathubela hasn't faced anyone remotely near Donaire's quality. Though he's a good boxer tutored by the highly regarded Nick Durandt, Mathubela isn't in Donaire's class.
The challenge for Donaire is to prove that. If Mathubela resorts to survival mode and tries what Narvaez did, or takes his foot off the accelerator like Vazquez did, Donaire needs to be able to adjust.
Superstars take these kind of opponents out, and Donaire is a budding superstar.
"The few previous fights I had I wanted to knock people out and that has been the reason why I had abandoned my jab and used counters more than anything," Donaire said. "When I do go back to my jab, there is no one in the sport who can match me when I do box.
"I don't want it to be a long fight. That is what I'm trying to say."
At the highest level of the sport, a win is significant. But Donaire is looking to place himself among the all-time greats. He's already won world titles in three weight classes and has dreams of going up at least – at least – two more.
Guys like Sugar Ray Leonard moved up, but when they did, they disposed of guys like Mathebula.
Donaire has the talent to be another Leonard, but the burden has shifted to him. He not only needs to go out and win, but also he needs to do so in impressive fashion.
No one is ever going to tab a guy who is content with safe low-impact decisions as an all-time great.
Donaire has that kind of potential, but at nearly 30, it's time for him to start fulfilling it.