NEW YORK -- The two men's quarterfinals on tap Thursday will showcase one pair of players with track records at this level and another that promises to be a potential rivalry of the future.
This rematch of the Olympic singles finalists features two of the most dynamic players in the game, both possessed of heavy, lethal forehands. Yet their recent past history has been one-sided in the left-handed Nadal's favor. He leads the career series 6-3, but Gonzalez hasn't taken a set off him in their past five matches, two of which were on hard court (including the Olympic gold-medal match). The Chilean's last victory over Nadal was in 2007, when Gonzalez was en route to an Australian Open finals appearance.
Neither Nadal's knees nor a strained abdominal muscle that troubled him a couple of matches ago were evident in his round-of-16 victory over France's Gael Monfils; in fact, Nadal has looked more authoritative with every match.
It's worth noting that Gonzalez by no means lives on his forehand alone. He defeated France's Jo-Wilfried Tsonga in the fourth round in part by besting him at the net with judicious, high-percentage volleying. But with this much on the line, Gonzalez is more likely to come unhinged if things aren't going his way. Who can forget his graphic, buttocks-dragging protest of a line call in his five-set semifinal against Robin Soderling at the French Open?
Nadal, on the other hand, is playing with less pressure than he'll have at any other major, and is motivated by the prospect of completing a career Grand Slam.
ESPN.com prediction: Nadal in straight sets.
These are two self-effacing, 6-foot-6-inch, 20-year-old guys who know how to play what John Isner's coach, Craig Boynton, would call "big man tennis,'' but one has a bigger serve and a bigger reason to believe in himself than the other.
Del Potro, who has been entrenched in the top 10 all season, has compiled a formidable record on hard courts in 2009, winning titles in Auckland and Washington, D.C., and twice stopping Andy Roddick in his tracks this summer. The Argentine almost derailed history at Roland Garros by putting Roger Federer on the ropes in their thrilling five-set semifinal before running out of gas.
Cilic broke through to reach his first Grand Slam quarterfinal by closing out a listless Andy Murray, who beat del Potro in the quarters here last year. The Croatian has won all three of his career ATP titles (including two earlier this year in smaller events) on hard courts.
Born five days apart -- they'll both turn 21 later this month -- Cilic and del Potro have played just once before, at the Australian Open earlier this year, where del Potro prevailed in four sets. At the moment, del Potro is a step ahead of Cilic in his evolution as an elite player. Based on recently gained experience and current form, del Potro should be able to dictate the pace of this match.
ESPN.com prediction: del Potro in straight sets.
Bonnie D. Ford covers tennis and Olympic sports for ESPN.com. She can be reached at firstname.lastname@example.org.