Like a roller coaster ride, this match, between two seemingly indefatigable warriors was thrilling, gut wrenching and heart stopping. Juan Martin Del Potro, the #24 seed, and 2009 US Open champion, defeated the #6 seed Dominic Thiem 1-6, 2-6, 6-1, 7-6, 6-4 in just over 3 ½ hours.

The atmosphere in the grandstand court was electric and eventually came to resemble a Davis Cup match with the Argentinian contingent chanting and rising to their feet whenever their countrymen hit a winner or broke serve.

In the first two sets, however, there was not much to cheer about; Del Potro looked weak and dazed and summoned the trainer before the end of the first set. Thiem, who turned twenty-four yesterday, remained composed and incredibly focused breaking the Argentine’s serve twice in the first set and hit nine winners. The Austrian was serving quite well and won 64% of first serve points.

Del Potro was 0/3 on break point opportunities and was unable to unleash on serve winning just 45% of first serve points and an even more dismal 33% on second serve points.

It was apparent to most in the stadium that Del Potro was ill.  We would soon learn that he was ailing from either a cold or the flu. He seemed lethargic and hesitant off the ground, committing 15 unforced errors.

The second set produced more of the same. Thiem was controlling the baseline and forecourt with his explosive groundstrokes. The backhand down the line and inside out forehand were outstanding and it seemed he would cruise to a straight sets victory with even better serving stats in the second set.

Once again, Del Potro was 0/3 on break point opportunities and was still way below 50% on second serve points won. He hit his first winner of the match in the second set but ended it with almost three times as many unforced errors.

The Argentine had never come back from 2 sets to love down in a grand slam tournament so given his compromised physical condition, it seemed highly improbable that he would reach that milestone this evening.

Del Potro closed out his first service game of the third set with an ace which as it turned out, radically changed the tenor of the entire match. He would begin to serve significantly better while Thiem served worse.

Del Potro won almost 80% of his second serve points while Thiem won a mere 44%. The two had almost an identical number of winners but Thiem produced almost twice as many unforced errors. Del Potro appeared to have awoken from a deep slumber. The tables had dramatically turned; Del Potro was 2/3 on break point opportunities while Thiem had none.

The Argentine had found his range on his formidable groundstrokes and utilized both the slice and two-handed backhand to control the points and secure the set 6-1.

Thiem served first in the fourth and held at love but would get broken in his next service game. Del Potro serving at 2-1 threw in a double fault to go down a break point which Thiem converted when Del Potro’s shot sailed long.

In the sixth game, Thiem would significantly elevate his level with three successive inside out forehands and a drop volley winner to earn a break point. While Del Potro received a time violation warning, Thiem ripped a backhand down the line to secure the break of serve.

Thiem had regained the momentum and up 5-2 in the fourth, was a game away from his first quarterfinal appearance at the US Open but Del Potro refused to yield. He held for 3-5 and then broke Thiem for 4-5 when the Austrian overcooked a forehand.

Del Potro held at love to even the set at 5 games apiece and Thiem held for 6-5 and once again found himself four points from victory. Del Potro would have to hold serve to force a tie-breaker but found himself down double match point following a couple of loose shots.

To the crowd’s amazement and utter delight, he saved them both with aces and drew an error from Thiem on the following point to level the set at six games all. Del Potro put on a clinic and rolled over Thiem to take the tiebreaker 7-1 and force a fifth and deciding set.

Although Thiem produced more winners than errors including three aces, he was unable to create any break point opportunities. While serving 4-5, his forehand let him down and on the heels of two forehand winners by Del Potro, was down match point.

This enthralling and captivating match, while heart stopping for all those in attendance and watching on tv, was for Thiem, heartbreaking. After 3 ½ hours of extraordinary ball striking, spirited competitiveness and swings of momentum, it ended on a double fault-just his second of the match.

Juan Martin Del Potro lives another day and will face Roger Federer for a place in the semifinals. Stay tuned-this matchup just might be another masterpiece.