The 35-year-old Spanish left-hander, who shares the all-time men's record of 20 Grand Slam titles with Novak Djokovic and Roger Federer, makes his US capital debut on Wednesday after a first-round bye at the ATP Citi Open.
"I'm excited," Nadal said Sunday. "I need to find again the level of tennis I need to be competitive. I hope to be able to find that in Washington. If not, hopefully in the next few weeks."
World number three Nadal skipped Wimbledon and the Tokyo Olympics after taking three weeks off to heal after losing to Djokovic in a French Open semi-final.
"My body decided for myself. If I had to choose, I will never miss Wimbledon and Olympics, but I was not able to compete in these events," Nadal said.
"I had some issues with my foot. I had to stop playing tennis for 20 days. Then I start practising, half an hour, then a little bit more. I went through the whole process.
"When I saw the calendar, I saw Washington as my goal and here I am. Missing Wimbledon, that was the right thing to do I think. The decision was the right one."
Nadal, seeking his 89th tour-level title on Washington's hardcourts, has spent the past month rebuilding his fitness but needs matches to make his next breakthroughs with the US Open in New York only four weeks away.
"I'm quite good," Nadal said of his physical condition. "I've been practising well at home but I need some competitive practices and to play some sets.
"I don't know how long it will take to recover everything. I'm here to try my best in every single moment."
When the Flushing Meadows fortnight arrives, Nadal will be seen as one of the few who might deny top-ranked Djokovic a calendar year Grand Slam after the Serbian star's wins at the Australian and French Opens and Wimbledon.
"When you win three, you can win four. He'll be playing on hard court, his best surface, so why not?" Nadal said.
"There will be other guys that want to achieve the last Slam of the season but he's probably the most favored player to achieve that, to achieve something amazing.
"I really believe he can do it without a doubt."
Nadal workouts popular
Nadal, who drew crowds in the main stadium for weekend practice sessions, is happy to play in front of a full capacity US venue for the first time since his 2019 US Open triumph.
"I'm excited to be back playing in America after more than a year of not playing here, especially with a full stadium we've not seen in such a long time," he said. "It's a great feeling and I'm really happy about it."
In his first match, Nadal will face either US wildcard Jack Sock or Japan's Yoshihito Nishioka. He could meet British seventh seed Cameron Norrie in the quarter-finals.
At the US Open, Nadal, 23-4 this year with titles on clay in Barcelona and Rome, will attempt to capture a fifth career crown and his 21st career Slam trophy, which would give him the all-time lead for the first time in his career.
The Spanish star has completed a career Grand Slam with a 2009 Australian Open title, Wimbledon crowns in 2008 and 2010 plus US Open trophies in 2010, 2013, 2017 and 2019 and a record 13 French Open titles.
Full capacity seating will be allowed this year at Washington after last year's event was wiped out due to the Covid-19 pandemic.