Brock Lesnar's big Wrestlemania match stems from UFC confrontation [VIDEOS]

On Sunday, Undertaker puts his undefeated streak on the line against Lesnar.

On Sunday, Undertaker puts his undefeated streak on the line against Lesnar.

:::: UPDATE :::: Brock Lesnar snaps Undertaker's Wrestlemania streak, shocks everyone [VIDEO and GIFs]

As discussed in this week's big pro wrestling cover feature, Sunday's Wrestlemania 30 is a pivotal show in World Wrestling Entertainment's history for reasons that go beyond 30 being a nice round number.

Though he won't be wrestling for the championship, University of Minnesota legend Brock Lesnar is involved in arguably the biggest match of the night. For the past two years, Lesnar has been a WWE part-timer, but his match against the Undertaker actually stems from a confrontation during his Ultimate Fighting Championship days.

See also:

Wade Keller: The man holding up the Pro Wrestling Torch [FEATURE]

In October 2010, Lesnar was defeated by Cain Velasquez in what would turn out to be his second to last UFC fight. (His career was cut short thanks in part to a intestinal disorder.) Mark Calaway -- a.k.a. The Undertaker of WWE fame -- was in attendance, and after the match, a reporter asked him for thoughts.

More Lesnar: Brock makes kickass return to pro wrestling [VIDEO]

A somewhat heated exchange with Lesnar ensued. (Though the encounter seems to be legitimate, or a "shoot," reports at the time indicated it was a pre-planned "work.")

Here's the video:

It took a few years, but WWE writers turned the confrontation into a wrestling storyline, or "angle," just in time to build to a Wrestlemania match.

The angle began in February with the Undertaker making a surprise appearance during Monday Night Raw and kicking Lesnar's ass during one of those awesome pro wrestling contract signing ceremonies:

But Lesnar got some revenge during the last Raw before 'Mania:

The last segment was meant to plant a seed of doubt about who's gonna prevail Sunday, but with Lesnar only wrestling part-time and Undertaker undefeated at Wrestlemania ("The Streak" is now up to 21), most wrestling observers expect Undertaker to go over (that is, win).

With his unique blend of massiveness, athleticism, and intensity, Lesnar was viewed early in his pro wrestling career as being well on his way to becoming the industry's top star. But he created a lot of hard feelings by abruptly leaving WWE to tryout for the Vikings in 2004, and it's no secret his heart isn't into wrestling.

See also: Jesse "The Body" Ventura played key role in decline of Minnesota wrestling [VIDEOS]

The topic of what motivates Lesnar to keep wrestling despite his apparent lack of enthusiasm was addressed by Wade Keller -- subject of our feature -- in a Q & A posted on this week.

Lesnar "is only in WWE for the massive money they pay him on a per-date basis," Keller writes. "What he cares about is maximum pay for minimum travel and time away from home."

But might Lesnar be excited by the prospect of once again winning the championship belt?

"If WWE paid him enough, I suspect he'd work more dates as champion, but only for a short stretch," Keller writes. "If they think offering him the belt would decrease his price, they haven't gotten to know him very well."

-- Follow Aaron Rupar on Twitter at @atrupar. Got a tip? Drop him a line at [email protected]