This is set to be Nagal's debut in a Grand Slam event.
This happened after he overcame Brazil's Joao Menezes in the final qualifying round.
It's a huge moment for Nagal.
Here are the details.
Nagal overcomes Joao Menezes to make the cut
The world number 190 beat 210th ranked Joao Menezes of Brazil 5-7, 6-4, 6-3 in the final qualifying round.
The 22-year-old became only the fifth Indian male player to feature in a Grand Slam singles main draw in this decade.
Somdev Devvarman, Yuki Bhambri, Saketh Myneni and Prajnesh Gunneswaran are the only Indian players who played at singles Majors between 2010 and present.
Two Indians to feature in men's singles main draw
The US Open 2019 will see two Indians in the men's singles main draw at a Grand Slam event.
This is a big spectacle for Indian tennis at the big stage.
Prajnesh Gunneswaran had made a direct entry to the main draw and will play Daniil Medvedev in the opening round.
Medvedev won the Cincinnati Masters recently in the build-up to the US Open.
Everyone dreams about this, says Nagal
"It means a lot. Everyone dreams about this. I played well in qualifiers. Every match meant something, I had some history with all of them. It was a roller-coaster. Of course, I am super happy. I don't even know what to say," Nagal told PTI.
I was hoping I get to play Roger someday: Nagal
Nagal has fulfilled his dream of wanting to play against Federer someday.
"It will be a great opportunity to play Roger at Arthur Ashe stadium. It's probably the best thing that could have happened. I was hoping I get to play Roger someday. He is God of tennis," added Nagal.
Bhupathi, Somdev praise Nagal ahead of Federer showdown
Playing Roger at the US open at night is every qualifier's dream and nightmare and I think this experience will both be a confidence booster for him," said Indian tennis legend Mahesh Bhupathi.
Somdev Devvarman highlighted Nagal's hard work behind this moment.
The progress you see is a testament to the hard work he put in, in the last two years with his team."
Nagal will hope to put forward his best performance
Earlier, Nagal had become only the sixth Indian player to win a junior Grand Slam title in 2015.
He had won the Wimbledon boys doubles with Nam Hoang Ly of Vietnam.
This is another big moment in the youngster's life.
Nagal will want to cherish this moment against one of the GOATs of tennis.
He will also hope to put forward his best performance.