Cincinnati - Third seed Rafael Nadal hit the wall with injury and Olympic fatigue, losing in the third round of the ATP-WTA Cincinnati Masters to Croatian teenager Borna Coric 6-1, 6-3 on Thursday.
Nadal, who won gold in the doubles in Rio last weekend, committed 18 unforced errors and four double faults in the first set alone as he joined Stan Wawrinka in making an early exit.
"I came here, I tried. I tried to do the right things to be ready, but it was obvious that I was not ready today," Nadal said.
Nadal received treatment to both his left elbow and left ankle after the opening set, while his left wrist, which forced him out of the French Open and to miss Wimbledon, was heavily taped as a precaution.
"I felt tired in the arm, elbow, shoulder. Two months and a half without competing, and especially without practising, and then do what I did in the Olympics, come here, different balls, too much," said the Spaniard.
"It's not the ideal situation to come back to the competition. After two months and a half and with an injury in the wrist, the normal thing is try to come back a little bit slower.
"But having the Olympics there I didn't have that chance. Now I pay for that. It was a little bit too much, my body hit the limit after the finish of Rio."
Coric took complete control as he won 10 games on the trot to lead 4-0 in the second set before wrapping up a crushing victory in 72 minutes.
For Coric, ranked 49th, it was just his second career win over a top-five player and also snapped a 10-match losing streak against opponents in the top 10.
"It was an unbelievable match from my side," said the Croat. "I played well from the beginning and he was not playing his best tennis.
"I served well and was hoping for some aces. That's what saved me."
Second seed Wawrinka slumped to a 6-4, 6-4 defeat to Grigor Dimitrov as the Bulgarian, fighting his way back after a poor season, reached the Cincinnati quarter-finals for the fourth time.
Wawrinka, coming off a back problem which kept him from the Rio Olympics, did not help his own cause with 28 unforced errors and just 11 winners in a contest that finished inside 90 minutes.
Dimitrov, who is playing doubles with Wawrinka this week as the US Open start approaches a week from Monday, stretched his lead in their head-to-head series to 4-2.
"I was fighting more the first set. I think I was very persistent in my service game. I knew that Stan will just come out and play good tennis," said Dimitrov.
"I think early on he really did. After an early break I felt like I got into his head and into his rhythm pretty well. I started moving the ball good and hitting my spots. That just helped me today."
Steve Johnson replaced John Isner as the top-ranked American thanks to a 6-3, 7-6 (8/6) upset of French seventh seed Jo-Wilfried Tsonga. Ninth seed Gael Monfils withdrew with back pain, handing a quarter-final place to Dominic Thiem.
In the women's third round, 2015 finalist Simona Halep beat Australian Daria Gavrilova 6-1, 6-2 while ninth seed Carla Suarez Navarro beat US Open finalist Roberta Vinci 6-1, 7-5. 15th seed Karolina Pliskova stopped Misaki Doi 7-5, 6-3.
Results from the fifth day of the Cincinnati ATP Masters and WTA hardcourt tournament on Thursday (x denotes seeded player):
Grigor Dimitrov (BUL) bt Stan Wawrinka (SUI x2) 6-4, 6-4
Steve Johnson (USA) bt Jo-Wilfried Tsonga (FRA x7) 6-3, 7-6 (8/6)
Dominic Thiem (AUT x8) bt Gael Monfils (FRA x9) walkover
Borna Coric (CRO) bt Rafael Nadal (ESP x3) 6-1, 6-3
Bernard Tomic (AUS) bt Kei Nishikori (JPN x5) 7-6 (7/1), 7-6 (7/5)
Milos Raonic (CAN x4) bt Yuichi Sugita (JPN) 6-1, 3-6, 6-1
Andy Murray (GBR x1) bt Kevin Anderson (RSA) 6-3, 6-2
Marin Cilic (CRO x12) bt Tomas Berdych (CZE x6) 6-3, 4-6, 6-4
Simona Halep (ROM x3) bt Daria Gavrilova (AUS) 6-1, 6-2
Carla Suarez Navarro (ESP x9) bt Roberta Vinci (ITA x6) 6-1, 7-5
Karolina Pliskova (CZE x15) bt Misaki Doi (JPN) 7-5, 6-3
Svetlana Kuznetsova (RUS x7) bt Timea Bacsinszky (SUI x12) 6-2, 3-6, 6-2
Angelique Kerber (GER x2) bt Barbora Strycova (CZE) 7-6 (7/5), 6-4
Tmea Babos (HUN) bt Dominika Cibulkova (SVK x8) 4-6, 6-3, 6-1