World number one Rafa Nadal is through but Germany's Angelique Kerber has become the first defending women's champion in over a decade to fall in the first round of the US Open.
The German sixth seed, who has not won a title since her victory at Flushing Meadows last year, was crushed 6-3 6-1 by Japan's 19-year-old Naomi Osaka.
The last defending women's champion to lose in the first round in New York was
Russian Svetlana Kuznetsova in 2005.
Kerber never got into the match against world number 45 Osaka who broke for 5-3 and sealed the opening set with a sizzling winner down the line under the closed roof at Arthur Ashe Stadium.
Men's top seed and current world number one Nadal overcame a slow start to beat unseeded Serb Dusan Lajovic 7-6 (6) 6-2 6-2.
While the year's final grand slam is just underway tennis fans have circled September 8th when, if all goes to form, Nadal could meet 16 times Grand Slam champion Roger Federer to decide a place in the final.
One of the great rivalries in sport, Federer, a five-times U.S. Open winner and Nadal, twice champion, have clashed 37 times over the years but never have they stood across the net on Flushing Meadows' hardcourts.
On French Open clay, Wimbledon's manicured lawns and in Australian heat, the elegant Swiss maestro and muscular Spaniard have played for titles and while no trophy would be on the line a New York meeting would still have the Big Apple buzzing.
After a sluggish run-up to the U.S. Open that included a shock round of 16 loss to Canadian teenager Denis Shapovalov in Montreal and another to Australian Nick Kyrgios in the Cincinnati quarter-finals, Nadal needed a few games to find his range against the 85th-ranked Serb.
The 21-year-old, chasing a first U.S. Open win, showed no sign of nerves, using his stylish groundstrokes to grab the early break on the way to 4-2 lead, the four games as many as he won in his only other meeting with Nadal, a round of 16 loss at the 2014 French Open.
But a steely Nadal found his comfort zone, breaking back at 5-5 to force the opener to a tiebreak that he took 8-6.
A ruthless Nadal delivered the young Serb another tennis lesson, breaking his opponent at the first opportunity in both the second and third sets to improve his record in first round U.S. Open matches to 13-0.