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Thunder Valley is famous for its own March Madness.

And plenty of drivers will enter Bristol Motor Speedway this weekend with unfinished business — dating from this season or last.

Combine 43 race cars with a half-mile short track, and tempers are bound to flare. In these tight confines, it’s the perfect recipe for retaliation among rivals.

Throughout 2011, there was no contest as heated as the one between Kevin Harvick and Kyle Busch. These guys despise each other on many levels — as both drivers and owners.

When Busch established Kyle Busch Motorsports, he hired Rick Ren from Kevin Harvick Inc. at the end of 2009 to be his director of competition.

The on-track escapades occurred later that year and escalated in the season finale at Homestead-Miami Speedway — when, with 25 laps remaining in the Ford 400, Harvick turned Busch's No. 18 M&Ms Toyota into a chocolate fondue inferno and claimed that Busch “raced me like a clown all day.”

Last year’s dustups between Happy and Rowdy weren’t extinguished before NASCAR put both drivers on probation for their antics at Darlington and parked Busch for dumping Harvick’s driver, Ron Hornaday, in the truck race at Texas.

Oh, and there was the afternoon at Kansas Speedway when Harvick’s team owner, Richard Childress, took Busch to the woodshed for roughing up another of his drivers, Joey Coulter.

But 2012 is a clean slate for these two. Harvick is out of the team-ownership business and focused on winning the title. It’s in his best interest to mind his own business and concentrate on the championship.

With just one Top 10 finish, Busch is 12th in Sprint Cup points. His extra-curricular racing has been curtailed — at least in the truck series — so he too can focus specifically on the Cup.

Still, it wouldn’t take much more than a spark to relight this feud. However, if these boys decide to behave, here are five other rivalries to watch:

1. Matt Kenseth vs. Brian Vickers — Kenseth was in the Chase for the Sprint Cup hunt last fall at Martinsville when Vickers tangled with the former champ and ended any opportunity of a second title.

Kenseth said that, at Daytona, the pair discussed their history, and that the bad blood is in the past.

For Vickers, this is the first opportunity he’s had to drive a Sprint Cup car in 2012. And he’s jumping into equipment that’s currently 10th in the point standings thanks to Mark Martin.

Bottom line: Vickers can’t afford to do anything stupid.

2. Matt Kenseth vs. Carl Edwards — There may not be two teammates who dislike each other more than Kenseth and Edwards.

While these two have tangled on short tracks before (remember Edwards' veiled rage at Martinsville Speedway in 2007), last weekend’s contact in the closing laps at Las Vegas cost Kenseth a top five finish.

3. Carl Edwards vs. Ryan Newman — If Kenseth is smart, and he most certainly is, he’ll allow Newman to do his dirty work for him.

Newman warned Edwards after their Phoenix altercation that he has one coming. Although Newman doesn’t believe their contact was intentional, the Rocketman was in a situation very similar to Kenseth — running in the top five in the closing laps when Edwards came a calling.

“I trusted him," Newman said. "Now he can't trust me because there is a lot to be had and lost; we lost a lot today. I don't know how much he lost, but that's not the point.

"I don't consider that a deliberate move by any means. We know plenty of times in this sport, what comes around goes around."

And when it comes to retaliation, no one gives better than Newman.

4. Kurt Busch vs. Jimmie Johnson — Since 2009, this battle of the champions has been boiling. It came to a head at Richmond last fall when Busch accused Johnson of winning his five titles due to top-notch equipment rather than talent.

Several earlier run-ins at New Hampshire and Pocono simply fueled the fire to this point. Now the dynamic of the relationship is further complicated by Busch’s new alignment with team owner James Finch, whose chassis and engines come from Hendrick Motorsports.

Given the slow start to both Busch's and Johnson’s seasons, it might be best to leave Bristol bouts to the amateurs.

5. Sticks and Stones, a/k/a #BEERWARS — Kevin Harvick and Brad Keselowski have carried their dislike for each other off of the racetrack and onto Twitter, where the battle of the breweries took a new turn on Tuesday night after a fan asked what type of beer to take to Bristol this weekend.

@KevinHarvick: Men drink Bud!

@Keselowski: @KevinHarvick Claims men drink bud. Idk about that, but I do know hot women drink miller lite. #JustSaying know who I wanna be liked by

@KevinHarvick: hear you comparing your beer to hot women? Where you hiding them?

@keselowski: Away from other drivers, 2 many babies. #somethinginthewater

@KevinHarvick: Good stuff!