U.S. Open Day 9 matches to watch

(UPDATE: Rain washed out play on Tuesday. These matches were rescheduled for Wednesday as part of a jam-packed order of play, weather permitting. For more previews of Day 10 matches, click here.)

Donald Young vs. Andy Murray (first match, Ashe): Unless someone spikes Murray's breakfast, this won't be a redux of their March clash at Indian Wells, where Young ousted the weary Scot 7-6 (4), 6-3 for the biggest win of his career. This is a different Murray in New York, as he admits he was stuck in a mental slump for months after his loss to Novak Djokovic in the Australian Open final. Sure, Murray's form can rise and dip from match to match, but Young doesn't have the power to bother the fourth seed. The American's game is not unlike the Scot's, reliant on movement and finesse to open up the court and go for winners. The difference here will be Young's serve, which is still a liability, and Murray's experience. You never know which Andy Murray will show up, but he has a pretty good track record once he gets past the first week of a Slam.

David Ferrer vs. Andy Roddick (first night match, Ashe): A battle of grinders, pitting Roddick's great serve against Ferrer's great return. Ferrer leads the head-to-head 5-3, and he beat Roddick in straight sets at Davis Cup in July in front of the American's hometown crowd in Austin, Texas. That loss will surely give Roddick the extra motivation he needs, but Ferrer is the in-form player. This one's going to have some rallies.

John Isner vs. Gilles Simon (first match, Armstrong): Big man vs. little man. Server vs. runner. You'd be hard-pressed to find a bigger contrast in styles and it's tough to know how it'll play out given the two have never met. Isner has quietly made it through his portion of the draw and is coming off a strong summer, while Simon has had to scrap and fight to make the fourth round, playing two five-setters and one four-setter. But his win over Juan Martin del Potro in the last round has to have buoyed him as he withstood a strong charge from the Argentine and wore down the big man. I suspect he'll be able to do the same thing to Isner.

Sam Stosur vs. Vera Zvonareva (third match, Armstrong):