Two-way jab clinics/fencing duels.

Yes - two fine jab technicians!

 

How about Conteh vs. Lopez? :deal

 

Eh...he used to have a beautiful Kronk-style jab, but Wladimir of late has fallen into the habit of using his far less aesthetically pleasing (and some would argue, illegal) Heisman-trophy push-pole extended-and-left-inert version of the 'jab'...and worse, only throwing real jabs exclusively as part of a 'jab-and-grab' combo.

Pulev vs. the Wlad of a few years ago would indeed be a very interesting chess match with the jab on either side of the board serving as the "queen", the most important piece in the arsenal.

 

Sergey Dzinziruk is an example of someone who lived and died by the jab all the way, racking up a 37-0 record without ever having anyone challenge the supremacy of his southpaw jab.

The best chance probably belonged to underrated LukᚠKonečný (who like Dzyna himself existed in the negative space between European level, which both were clearly superior to, and world class elite status, which both of them as WBO titlists came near but didn't penetrate), but the Bohemian pug fought the wrong game plan, completely eschewing his decent left jab and forgetting the #1 rule of dealing with southpaws: make them circle into a straight right hand as often as you can - instead proving overly reliant from the opening bell on left hooks to Dzinziruk's well-protected body and head, with the occasional lunging overhand right.

Dzinziruk beat Konečný - along with 36 others - with jabs alone.

Then he took his cash-out opportunity, moving up to middleweight to challenge Sergio Gabriel Martinez.

He was a 4/1 underdog, but his saving grace was thought of as his busy, stinging, accurate jab. If he could disguise it and keep his timing down, maybe he could have pockets of success keeping Maravilla honest and trampling his rhythm on the outside, with that stick of his. Martinez was never considered much of a jab-dependent boxer. It just wasn't part of his routine, at least not in the form of a standalone or set-up punch. (he did throw what technically could be termed jabs, since they were his lead right hand thrown straight, but primarily just in the midst of combinations)

Martinez took him to school and raped him with jabs (rendering Dzinziruk's own completely impotent) en route to a TKO after scoring five knockdowns, all set up by the jab.

http://www.dailymotion.com/video/x10eim3_sergio-martinez-vs-sergeuy-dzinziruk_sport

Jab stats:

Martinez 147 of 384, 38%
Dzinziruk 80 of 242, 33%

Martinez averaged 18 landed of 48 thrown per round that night. (double the middleweight average)

A bit too one-sided to join those listed in the OP and some of the other great suggestions in here, but an interesting case of a non-jabber completely dismantling a jabber with his own weapon.

 

:good


Oscar is anomalous. He could have gone down among the ATG jabbers in his weight range (and been the preeminent one in his generation alongside Ike, sharing his throne) but he was just so goddamn inconsistent with it, from the very beginning until the very end in the pros. In the amateurs he was very much a by-the-book jab-first boxer and had not yet fallen in love with his left hook.

 

His jab is as effective as it gets, especially when he throws it downstairs into opponent's diaphragm making them rein up short and suck in a sharp breath, completely disrupting all their forward momentum.

HOWEVER, you can't really call Mayweather a 'jabber' by trade because he makes so little use of it and sometimes goes entire nights barely unsheathing it. He doesn't need his jab, he just keeps it on standby as one more effective tool he can toss in the mix. (but rarely deigns to)