Rafael Nadal showed the rust from his long layoff with a wrist injury on Thursday, losing in straight sets to Croatia’s Borna Coric at the Cincinatti Masters.
The 30-year-old Spaniard was sluggish and well off the mark with all of his shots as Coric grabbed control and won 6-1 6-3 in an hour and 11 minutes.
The 19-year-old reached the quarter-finals of a Masters tournament for the first time and ended his streak of 10 straight losses against Top 10 opponents.
The upset left only one member of the Big Four still in the running.
Defending champion Roger Federer and top-ranked Novak Djokovic are missing the tournament because of injuries.
Andy Murray is playing, but feeling the effects of a gruelling week in Rio de Janeiro where he won the gold medal on Sunday.
Along with Nadal, those four have combined to win 54 of the last 58 Masters events.
Nadal missed two months because of an injured left wrist and returned to the courts in Rio, where he lost in the semi-finals.
The lack of matches showed in Cincinnati: Nadal double faulted five times and had 27 unforced errors. Coric surged ahead 4-0 in the second set and closed it out.
Steve Johnson also advanced to the quarter-finals on Thursday and put himself in position to become the top American in the ATP rankings heading into the US Open.
Johnson beat Jo-Wilfried Tsonga 6-3 7-6 (8-6) and raised his index finger in celebration.
He’ll move into the ATP’s top spot next week, knocking John Isner out of the slot that he’s held every week since July 29, 2013. Isner lost in the second round in Cincinnati.
“Hasn’t sunk in yet,” Johnson said.
“I just found out. So it’s an honour, it really is. John has held that spot for a while, and I’m just glad that there are a bunch of Americans pushing toward the top.”
Second-seeded Stan Wawrinka wasted a chance to take advantage of the wide-open draw on ?Thursday, losing to Bulgaria’s Grigor Dimitrov 6-4 6-4.
Wawrinka smacked his racket on the ground as he fell behind in the first set, the start of a frustrating match overall. Tied 3-3 in the second set, Wawrinka committed two unforced forehand errors and Dimitrov got the break he needed to take control.
Wawrinka had one of those few Masters titles that wasn’t claimed by the Big Four, winning in Monte Carlo in 2014.