Rafael Nadal lost 7-6(9), 4-6, 6-3 to Borna Coric at the Cincinnati Open on Wednesday in the Spaniard's first match since pulling out of the Wimbledon semifinals due to injury, dealing a big blow to his preparations for the US Open.
The 22-times Grand Slam winner had been hoping to get as many matches under his belt as possible after returning from an abdominal injury but losing to the Croat means he heads to Flushing Meadows well short of competitive action.
Taylor Fritz blasted his way to a 6-3, 6-2 win over Australian Nick Kyrgios while Cameron Norrie fought back to beat former world No. 1 Andy Murray 3-6, 6,-3 6-4 in an all-British clash.
After an hour-long rain delay, Coric, who returned to the Tour in March after a lengthy absence due to a shoulder surgery, edged a nail-biting tie-breaker to take the opener after each players had saved two set points.
With the crowd firmly behind Nadal, the 36-year-old roared back into the contest by breaking former world No. 12 Coric's serve midway through the second set to force a decider.
But Coric, now ranked 152nd, got his only break of the left-hander's serve for a 4-2 lead and then sealed his spot in the third round with an inside-out forehand winner on his first match point after two hours and 51 minutes.
"It has been very, very special," Coric said after his victory over world No. 3 Nadal, who won the Australian and French Open titles in an injury-plagued season.
"I was honestly just looking forward to playing this match as I haven't had that in the last two years. Now that I won, it's kind of crazy."
Coric will next play another Spaniard in Roberto Bautista Agut, who defeated home hope Marcos Giron 6-3, 6-3.
The upset of the day went to American wild card Ben Shelton after the 19-year-old continued his dream ATP Masters debut with a 6-3, 6-3 win over world No. 5 Casper Ruud.
A day after taking down Lorenzo Sonego, the 229th ranked Shelton needed just 68 minutes to beat Ruud and advance to a third-round match against fellow left-hander Norrie.
American No. 1 Fritz sent down 16 aces to come out on top against Kyrgios, with the Australian firing just seven of his own and offsetting most of those with six double faults.
The 11th-seeded Fritz needed just 51 minutes to hand Kyrgios his second defeat since losing to Novak Djokovic in the Wimbledon final.
Such was Fritz's domination on serve that Kyrgios could not muster a single break opportunity, while the 24-year-old American converted three of his seven chances.
"It feels great to have my game come together today," said Fritz. "That’s the kind of match I really needed to give me a lot of confidence going into the next match, going to the US Open, a lot of things are clicking for sure."
Fritz will next meet sixth seed Andrey Rublev after the Russian scored a 6-7(7), 7-6(3), 6-2 win over Italy's Fabio Fognini.
Fourth seed Stefanos Tsitsipas of Greece sailed into the third round with a 6-3, 6-4 victory over Serbian Filip Krajinovic while Pole Hubert Hurkacz, runner-up in Montreal on Sunday, lost to his doubles partner this week, American John Isner, 7-6(5), 6-7(5), 6-2.
It was a good day for Canada with both seventh seed Felix Auger-Aliassime and Denis Shapovalov picking up victories.
Auger-Aliassime cruised past Australian Alex de Minaur 6-3, 6-2 while Shapovalov rallied for 3-6, 6-4, 6-3 win over in-form American Tommy Paul to register back-to-back victories for the first time since May.
Shapovalov will take on world No. 1 Daniil Medvedev next while Auger-Aliassime meets Italian Jannik Sinner.