US Open Tennis 2013: Biggest Takeaways from Day 7's Early Action

Juniors and doubles matches dominated most of the early Day 7 schedule, but bold statements were made by a few of the top seeds in the men's draw.

Andy Murray (3), Stanislas Wawrinka (9), Tomas Berdych (5) all advanced into Round of 16, but only two looked dominant in the process. 

Berdych and Wawrinka will face one another in Round 4, but we'll have more on that later.

With some dynamite matches still on the schedule for Sunday afternoon/evening, it's a beautiful day to be a tennis fan.

These are the biggest takeaways from the early action.

Berdych vs. Wawrinka Should Be an All-Out Brawl

When Berdych and Wawrinka step onto the court in Round 4 of the 2013 U.S. Open, it will mark their 12th career match against one another. 

In 11 previous matches, Wawrkinka holds a slight edge, having won six times. 

The duo last met in May in Madrid, when Wawrinka defeated Berdych in the semifinals, only to later lose to Rafael Nadal in the final.

Only five of the 11 matches between these two top players has been won in straight sets, which further attests to the highly competitive nature of this rivalry. 

Berdych has skated through the first three rounds, winning all three matches in straight sets. Wawrinka, on the other hand, was pushed to four sets in his last match and has been his usual up-and-down self.

Though Berdych would appear to have more momentum heading into this match, he's lost to Wawrinka four out of the last five times, as noted by Chris Skelton of Tennis View Magazine:

While it's impossible to predict who will win, you can be sure this fourth-round match will feature plenty of excitement. 

Andy Murray Looking Good in Title Defense

Heading into the 2013 U.S. Open, Murray had suffered through, what appeared to be, a post-Wimbledon hangover. He was ousted relatively early in two tournaments after winning his first Wimbledon title, and many wondered how he'd fare in New York this summer.

After three rounds, it's clear there was no reason to worry. Murray is in excellent position to defend his U.S. Open title. 

An easy win in Round 1 was followed by a sterner test in Round 2. Murray overcame a late rally by Leonardo Mayer, who stole the third set of that match, to win in four sets.

He bounced right back again in Round 3 with a resounding, straight-sets victory over Germany's Florian Mayer, as noted by US Open Tennis:

Strong shot-making and relentless defense highlighted Murray's performance against Mayer. His next opponent is Denis Istomin, who has never before gotten out of the third round in the U.S. Open. 

Murray should cruise into the quarterfinals, where he'll face the winner of the match between Berdych and Wawrinka. 

Follow me on Twitter @JesseReed78