The sixth-seeded del Potro had just come off a stunning win over Marin Cilic in the quarterfinals and again didn’t flinch or waiver in front of a packed Arthur Ashe Stadium for Sunday’s semi against No. 3-seed Nadal. With his wide wingspan and amazing foot speed, delPo started picking apart Nadal’s game early in the first set, never letting the Spaniard establish a rhythm or a strategy, often keeping Nadal in a defensive position 6 feet behind the baseline.

When Nadal would hit hard, del Potro would feed off his pace. When Nadal tried the soft slice hoping delPo would overhit for the error, the Argentine only accommodated him a few times. Mostly, del Potro was a wrecking ball, pushing Nadal around the court, matching shots and moving with graceful savvy for muscular man of 6-foot-6.

In the last game of the first set, Nadal had overcome some break points to arrive at deuce, only to be outplayed by delPo, who hit the winner to take the set. The second set went basically the same. Nadal tried again to find a way to upset del Potro’s rhythm, but the big guy with the laser passing shots and the soft touch at net kept hammering away at Nadal’s game, finding every hole.

At the start of the second game of the third set, a fan yelled “C’mon Rafa, I believe,” but belief just wasn’t enough as del Potro broke early to go up 2-0. At 4-2 with delPo serving, the crowd cheered hoping for a Nadal comeback. He momentarily made a couple of noteworthy shots to go to 30-30 but was quickly deflated as del Potro hit a winner and proceeded to hold at 5-2. Nadal served the final game, only to be broken again.

While the unforced error count for these tennis titans were fairly even, del Potro’s first- and second-service percentages were decidedly better, as were his number of winners.

Nadal’s own assessment of his performance was straightforward. Even though he played with abdominal muscle strain, he invoked no excuses. “It was a very difficult match today; he played really well, much better than me. I had a lot of chances. Playing semifinals was very important result for me. I know if I really want to compete, I need to be in perfect condition physically and play better. In general I’m very happy how I came back.” When asked how he approached the big points, Nadal laughed and said, “Not the right way today.”

In the post-match on-court interview, a grateful del Potro cited the US Open as his “favorite tournament.” When the comment was made about the expected Nadal-Federer final, the big Argentine told the crowd, “I’m sorry,” to the laughter and appreciation of the fans. Then he added, “I will fight for every point for everyone. This is the best moment of my life.”

Later, in his press conference, a calm, smiling delPo said, “This final is part of my dream, but this moment I’m very happy to beat Rafa in straight sets.” When asked about the final, acknowledging that he may be facing Djokovic, he replied, “I have to play better than today because I never beat Djokovic also. Both [Federer or Nadal] will be tough, but I will try.” He may have a great shot at it.