While the year's final grand slam is only just underway tennis fans have circled Sept. 8 when, if all goes to form, Nadal and Federer would meet in the last four 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.
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Federer will follow Nadal on to Arthur Ashe Stadium later on Tuesday looking to hold up his end of the deal when he takes on American Frances Tiafoe.
"Today I won. That's the most important thing for me," Nadal told reporters. "I believe that I am ready."
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 the second and third sets to improve his record in first round U.S. Open matches to 13-0.
"Tough beginning of the match," said Nadal, who will next meet American Tommy Paul or Japan's Taro Daniel.
"The important thing is to win because is normal that you have some nerves at the beginning and you get a little bit tight at the beginning of the tournament.
"So important thing is be through and that's what I did today."
(Editing by Ed Osmond)
