KEY BISCAYNE, Fla. -- Moments before the match, Tommy Haas sat in his changeover chair jiggling his legs, eager to face the world's No. 1-ranked player and old enough to know such chances don't often come along.
Haas took advantage Tuesday night, beating three-time champion Novak Djokovic in the fourth round of the Sony Open 6-2, 6-4. The upset snapped Djokovic's 14-match winning streak at Key Biscayne, where he won the tournament the previous two years.
Eight days shy of his 35th birthday, Haas became the oldest man in 30 years to beat a No. 1 player.
"Playing against someone like Novak and coming out on top at this time of my career, it's unbelievable," Haas said. "This is what I play for."
Haas improved to 2-14 versus No. 1 players. His only other win came against Andre Agassi in 1999.
The top-ranked Djokovic has lost two of his past four matches after winning 22 in a row, including the Australian Open for his sixth Grand Slam title.
"All the credit to Tommy," Djokovic said. "He played a great match and he was the better player, no question about it."
The oldest player in the top 50, Haas is making his 13th appearance at Key Biscayne and advanced to the tournament's quarterfinals for the first time. His opponent Wednesday night will be No. 11 Gilles Simon, who rallied past No. 7 Janko Tipsarevic 5-7, 6-2, 6-2.
With Rafael Nadal and Roger Federer skipping the tournament, Djokovic's defeat clears a path for Andy Murray, the 2009 champion and 2012 runner-up.
He beat No. 16 Andreas Seppi 6-2, 6-4 and was to play Wednesday against No. 9 Marin Cilic, who defeated No. 6 Jo-Wilfried Tsonga 7-5, 7-6 (4).
No. 3 David Ferrer will play unseeded Jurgen Melzer on Wednesday. No. 4 Tomas Berdych will face No. 8 Richard Gasquet on Thursday.
Sam Querrey lasted only 50 minutes in the fourth round and lost to Berdych 6-1, 6-1. Querrey was playing his first tournament as the No. 1 American on the ATP Tour, and his elimination means that for the first time, the 28-year-old tournament will have no U.S. men in the quarterfinals.
The shutout is the latest sign of declining fortunes for American tennis.
"I guess you could say it's been somewhat of the norm the last couple of years," Querrey said. "It's not like we had guys in the quarters week in, week out."
American results on the women's side have been better lately, thanks mostly to No. 1-ranked Serena Williams. The five-time Key Biscayne champion advanced to Thursday's semifinals and tied the women's record for career victories in the tournament by beating No. 5-seeded Li Na 6-3, 7-6 (5).
Williams' opponent in the semifinals Thursday will be defending champion Agnieszka Radwanska, who hit a desperation shot behind her back for a winner en route to a win over No. 30 Kirsten Flipkens 4-6, 6-4, 6-2.
With temperatures in the 50s for the final match of the night, Djokovic appeared out of sorts from the start. During his second service game, he became annoyed at fans shouting as he was about to serve.
"It's definitely the worst match I have played in a long time," Djokovic said. "I just didn't feel good on the court. Conditions were really much, much different from what I have played in previous matches. Balls didn't bounce at all."
For the final few games, Haas wore a lavender shirt, a red sweatband, black shoes with lime trim and a blue cap. In other words, he won ugly.
"Yeah, I'm pretty pathetic I think when it comes to color matching," he said. "Sometimes I look at myself in the mirror before I go out and I'm like, 'Geez, what was I thinking?' I guess if I maybe had a clothing contract it would be different."
Haas, who is ranked 18th, has been as high as No. 2 -- way back in 2002. He tumbled to No. 373 at the beginning of 2011 after hip and elbow surgery.
The German closed out the victory with a forehand winner, then shared a warm exchange at the net with a gracious Djokovic, who gave the crowd a wave as he left the court.
"I was fighting," Djokovic said. "I was trying, all the way up to the last ball. There are days where you just don't feel good on the court. Nothing really goes your way. This is one of those days. But all the credit to him for making me play this bad."