Brock Lesnar vs. Undertaker: Best Possible Outcomes at WWE SummerSlam 2015

It's without doubt the headline match of the summer—and the rematch fans have been waiting to see for well over a year.

When Brock Lesnar and Undertaker square off in the ring at SummerSlam on Sunday, it will dominate the sports entertainment world in a similar fashion to how it did at WrestleMania XXX last year.

And while there was a surprise in the outcome last year with Lesnar ending the streak to the surprise of everyone, this year, any outcome wouldn't rank as anywhere near as big of a surprise as that.

But when the bell rings and these two icons lock horns on Sunday, what would be the best and most realistic outcomes in the main event at SummerSlam?

Brock Lesnar Wins Cleanly

Hang with me on this one. Sure, a Brock Lesnar clean win against Undertaker for the second straight meeting between the two might not be the best result for some people, but given how we're not entirely sure how long Undertaker is sticking around at the moment, would him winning clean benefit anyone?

He doesn't need a win to secure his legacy. He doesn't need to beat Lesnar to ensure he's one of the greatest of all time. And given how Lesnar is sticking around for the next few years after him re-signing with the company, it might be more important to preserve his status as the unbeatable beast.

Undertaker has made Lesnar look more vulnerable than arguably anyone since he returned to the company. Since then, he's beaten the likes of Triple H and John Cena with little trouble for the most part, and the way Taker is tormenting Lesnar is justification enough that he is a bigger threat to Lesnar than anyone else is.

What would be best would involve Lesnar being pushed to his very limit for getting a win—but only just. No Suplex City marathon like against Cena at SummerSlam, and no brutal destruction. 

Just have Lesnar be pushed to his very limit and be seriously tested. It would keep his long run of not being pinned in tact and set him up to move on to his next challenge.

The Brothers of Destruction Reunite, Temporarily or Permanently

You almost get the feeling that there's going to be a twist in the main event. After all, it is SummerSlam, and it is two guys who would be better off not losing.

So if one of them is going to come up short, why not have a controversial finish and maintain some momentum?

And while we're at it, why not reunite one of the most feared and dominating tag teams of the last 15 years in the process? 

Undertaker's brother Kane was written off WWE TV by Lesnar dismantling his ankle on the steel steps during a taping of Raw heading toward the match between The Beast Incarnate and Seth Rollins at Battleground. In order to avenge that beating, why not have the old, demonic Kane return to unite with his brother and help him beat the one man he couldn't beat?

It would set up a compelling few weeks as Lesnar tries to sink The Brothers of Destruction, but of course it's heavily reliant on Undertaker sticking around after WrestleMania. If he does, this could be an opportunity well worth exploring.

Undertaker vs. Sting Finally Comes to Fruition

Yes, it's an obvious and well-documented finish, but there's a reason it's being talked about so much: It would be simply sensational.

Ever since Sting signed on the dotted line with WWE, fans have been questioning and demanding when that dream match between The Icon and Undertaker is going to take place. A match at WrestleMania 31 didn't come to fruition, and looking back at their respective matches at the show earlier this year, it could go down as a missed opportunity.

Credit: WWE.com

Undertaker's win against Bray Wyatt and Sting's loss to Triple H weren't really standout matches or even rivalries, so perhaps WWE may opt to roll the dice at SummerSlam.

Imagine the scenario: Lesnar is again being beaten by Undertaker, and he's about to hit the Tombstone Piledriver to finally put him away. The lights then drop, and when they come back up, Sting has dropped down from the rafters and is standing in the middle of the ring, eye-to-eye with the great foe he never faced.

With baseball bat in hand, Sting beats down Undertaker, much to the delight of the fans inside the Barclays Center. After all, Undertaker has been playing the role of a heel building up to this match, so Sting could easily come in and play the role of a babyface.

It would be a dramatic and scintillating finish to the show—and set up Night of Champions to perfection.