Ever since he first appeared on premium cable four years ago, unbeaten Terence Crawford instantly became a fighter to watch thanks to his almost unlimited potential.

With long arms and a mix of speed and surprising power, it didn't take long for Crawford to prove in subsequent fights that he's more than just a slick boxer. By winning titles at lightweight and junior welterweight, the native of Omaha, Nebraska showcased an almost predestined instinct to finish. 

The result has been almost universal praise for Crawford (30-0, 21 KOs) as one of the top pound-for-pound boxers in the world. In his biggest fight to date, during last July's 140-pound title unification bout against unbeaten Viktor Postol, Crawford was dynamic in proving that he's simply on another level. 

But if there's one problem when talking about Crawford's greatness, it's that we haven't consistently seen it against the very best. In fact, outside of the Postol victory and his 2014 coming-out party against the much-smaller Yuriorkis Gamboa, Crawford has regularly feasted on smaller and less skilled opponents who hovered much closer to average than very good or great. 

Of course, that hasn't exactly been his fault as Crawford sits on the wrong side of boxing's political divide when it comes to finding top opponents around his weight class. Making matters worse has been the fact that Manny Pacquiao, who shares the same promoter in Top Rank, hasn't appeared interested in any kind of formal passing-of-the-torch event. 

At 29, we know that Crawford is great. But just how great? It's hard to tell. 

We should have a bit more answers come Saturday when Crawford defends his titles against arguably his most talented opponent to date in Olympic gold medalist Felix Diaz (19-1, 9 KOs) of the Dominican Republic. Raising the ante on the prestige of the bout is the fact that it doubles as Crawford's debut inside the big arena at New York's Madison Square Garden (HBO, 10:15 p.m. ET/PT). 

The fact that the fight was even made was a bit refreshing considering Diaz, 33, is both dangerous and not well known beyond boxing's hardcore fan base. He also resides on the other side of the aforementioned street when it comes to boxing politics. 

With Crawford out of better options, a deal was hatched. But despite the respect he has for Diaz's craft, Crawford isn't so sure this will be the most dangerous challenge he has yet to face. 

"We shall see," Crawford said. "A lot of people look a the fights and ask 'who will bring out the best in Terence Crawford, who is going to bring out this in Terence Crawford, we want to see Terence Crawford in these types of fights.'  But again, I make my adjustments and it's just that. So we are going to have to see how the fight is going to go or what is going to happen. I just fight the fight."

Diaz, a southpaw, is both slick and tough at the same time. He's not afraid to mix it up on the inside and looked strong in his only defeat, a 2015 majority decision loss to former titleholder Lamont Peterson, in which most observers felt Diaz got a raw deal. 

"I know how good Crawford is. Felix knows how good Crawford is. The media knows how good Crawford is, but he is not God, he is not unbeatable," Diaz's promoter Lou DiBella said. "[Crawford] has had tough fights and I think he has had tough fights with guys like Gamboa, who was a little guy who gave him a tough fight for a while and Diaz has a lot of the same attributes when it comes to pressure and style which could make it a very difficult night for 'Bud.'  Felix has wanted this fight forever."

Diaz, who worked with well-respected California trainer Joel Diaz, is just happy to get the opportunity.  

"I called out Terence because Terence is the best in the division," Diaz said. "With his style, I know I can beat Terence Crawford. He has fought no one like me.  I am definitely motivated that I am being overlooked and that I am the underdog."

Prediction

If Crawford's speed, length and technique hasn't been enough to befuddle opponents, his mid-fight adjustment to southpaw has usually been the trick to open up new angles and allow him to control. But he'll be in there against a fighter far more skilled than he is used to, and someone much more comfortable trading shots on the inside. 

Because of that, Crawford's jab and length will be key in order for him to control distance and keep the fight on his own terms. He also might find success forcing the natural counterpuncher in Diaz to take the lead, which could open up doors for countering. 

When it comes to Diaz, he tends to do his best work off the clinch, digging to the body and mixing in well-timed uppercuts. If he can corner Crawford and turn it into a fight, the advantage will likely dip his direction. 

Diaz isn't your typical brawler or pressure fighter. His pedigree is way too strong. But that's why he's dangerous on the inside. For a fighter as skilled as he is, he has no problem fighting from the trenches and used his combination of speed and accuracy to take over fights. 

For as aggressive as Crawford has been against limited opponents, he has always given the appearance that he could fights much easily by removing the entertainment value and boxing from distance. His early wins on HBO in safe performances against the likes of Breidis Prescott and Andrey Klimov showcased that. 

As long as Crawford avoids getting into a war that isn't necessary, he should be able to outwork Diaz and win a boxing match. It won't be easy and should challenge him in ways he hasn't. But  if we have learned one thing about Crawford up to this point, the more that's demanded of him, the more he shines. Pick: Crawford by unanimous decision.