ESPN 2008 US Open

NEW YORK -- Only 16 months separate Sam Querrey and Rafael Nadal in age, but at 22 and 20 respectively, there's a vast divide between their résumés. That permitted Nadal to say, without a trace of irony, that Querrey "has a great future" after the American stretched Nadal out in his 6-2, 5-7, 7-6, 6-3 round of 16 U.S. Open win.

While Querrey would have loved to have seen the future arrive Monday against the world No. 1, he drew some satisfaction in overcoming a nervous start in his first visit to center court and giving Nadal all he could handle at critical junctures in the match.

"I thought I was maybe going to lose like 2-2-0 or something,'' said Querrey, who upset two seeded players, the Czech Republic's Tomas Berdych (22) and Croatian ace machine Ivo Karlovic (14) en route to his date with Nadal. "As it went on, I was kind of finding myself out there, and I was feeling good and, you know, mellow and calm and relaxed."

Querrey looked sunk in the second set when he trailed 4-2 and faced break points on his serve. But he staved off Nadal, broke him at love to even the set at 5-all and painted the lines in Nadal's next service game to the roaring delight of the Ashe crowd. It was the first set Nadal has dropped in this tournament.

The American's supporters included a group of friends from his hometown of Thousand Oaks, Calif., dressed as Samurai (emphasis on the Sam) who took a red-eye flight to see him play. He made it worth their while by again coming from a break down to push Nadal to a tiebreak in the third set, and appeared ready to rise from the competitive grave once more in a thrilling seventh game in the fourth set that went to seven consecutive break points.

"He had to earn it," Querrey said. "I didn't just give it to him."

Querrey is ranked 55th after reaching a career-high No. 38 in May thanks to his first ATP title in Las Vegas and an unexpected quarterfinals appearance on clay in Monte Carlo, where he defeated then-No. 9 Richard Gasquet of France.

In his second full season as a pro, Querrey has been trying to augment an arsenal that already includes a powerful serve and an increasing variety of effective forehands with and without spin. He's refining his backhand and working on his fitness -- the latter with the help of Andre Agassi's former workout guru Gil Reyes -- to layer muscle and stamina onto his 6-foot-6 frame. "Felt like I could have gone five sets,'' he said confidently.

Querrey will crack the top 50 again by virtue of his best performance in a Grand Slam event. Always charmingly blunt, Querrey said he won't consider the season a success unless he can scramble up into the top 32 and earn a seeding at next year's Australian Open.

Nadal, who called the match "crazy," looked relieved when it was over. "I think he start[ed] playing not very good, and later he play[ed] better,'' said Nadal, who will face another American, Mardy Fish, in the quarterfinals. "But he's a good player, no? We know that.''

Bonnie D. Ford covers tennis and Olympic sports for ESPN.com. She can be reached at bonniedford@aol.com.