It's the main event; here's why I like a Roddick upset

	Roger Federer (left) has beaten Andy Roddick in six straight finals in official ATP events, dating back to Wimbledon '04. Manny Millan/SI (2)
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Are you pumped or what? The blockbuster semifinal of the Australian Open is near, and it's between seemingly invincible world No. 1 Roger Federer and the significantly improved Andy Roddick. This is what we call in the locker room a "popcorn match," meaning that we're looking forward to it so much that we want to grab a nice bowl of popcorn, get comfortable and settle in for a heck of a battle.

As I wrote in my last column, Roddick is primed for this tournament. He is playing the best tennis of his career -- his movement, backhand and transition game have all made significant strides recently -- and has an infusion of confidence from his new coaching relationship with Jimmy Connors.

Andy has shown that he is bridging the gap between Federer and himself, winning a set in last year's U.S. Open final, taking him to match point in Shanghai in December and beating him in the Kooyong warmup exhibition prior to the Aussie Open.

Andy knows how he has to play to beat Federer, and while it's easier to draw it up on a chalkboard than actually execute it, his improvements in the aforementioned areas give him the tools to do it. Andy is one of the few players who can successfully take Federer's time away. He can overpower Federer with his powerful serve. Moreover, with his increased comfort and proficiency at the net, Andy now has a way to rush Federer when his serve comes back.

Andy has spent endless hours improving not only his volleying, but also his approach shots and net coverage. When I was in Hawaii with him last month, we spent much of our practices re-enacting patterns of play where he would approach and have to win points at the net. I believe this, in addition to the technical improvements Connors has made to shore up Andy's backhand, will make a significant difference on Thursday.

Everyone knows Roddick has a huge serve and forehand, but Federer figured out how to neutralize them by blocking back his return and using his short, hard slice to lure Andy into the net in defensive or neutral situations. Now that Roddick is more comfortable attacking the net and is mixing up his serve and volley more, Federer has many more variables to consider when trying to neutralize all of Roddick's weapons.

All that being said, he's still Roger Federer! The Swiss master will surpass Pete Sampras' all-time Grand Slam victories total in the next few years and he always looks like he knows what to do and how to do it. The biggest and most underrated attribute Federer possesses is his movement. He is one of the great movers in tennis history, and what his speed gives him is a commodity that is worth its weight in gold on a tennis court: time. The reason Federer rarely seems rushed is because he isn't. He's usually at the ball and prepared to hit it with plenty of time to spare.

Federer is like a ballerina, moving in slow motion and measuring each and every shot. Every time I watch him I think to myself, I'm just going to do that next time I play; that looks way easier then whatever it is I tried to do during practice today.

But the gap between Roddick and Federer shouldn't be as wide as it is. With Andy starting to tap into his potential on a more consistent basis, he's one of the few players that can challenge Federer. I think the semis of this Australian Open is a great opportunity for him to do just that.

I'm going to go with the upset and pick Andy in five tough sets.

Outspoken ATP tennis pro Justin Gimelstob is a frequent contributor to SI.com. He is currently recovering from back surgery after his 11th year on tour.