New York - Rafael Nadal doesn't quite know what to expect as he heads into the second week of the US Open for the first time since his second title run in 2013.
The fourth-seeded Spaniard looked in fine form in a 6-1, 6-4, 6-2 victory over Russian Andrey Kuznetsov.
But with the memory of his forced retirement from the French Open with a wrist injury that also caused him to miss Wimbledon still fresh, Nadal is taking nothing for granted.
"I don't know in which kind of level I am," said Nadal, who won titles in Monte Carlo and Barcelona before his season was interrupted.
He's in the second week of a Grand Slam for the first time since he reached the quarter-finals at Roland Garros last year.
"It's true that when I had to stop I was playing great. I felt myself ready for the French. I don't know where I am today. Only thing I know is I am happy.
"I am excited to play the US Open. For me it's great news that I am on the tour again, and I am playing every day with less pain on the wrist.
"That's most important thing."
Nadal was all but flawless in the opening set on Friday, but wilted a little as Kuznetsov stepped up the attack in the second.
"I lost the serve in the second for a couple of games. I was serving bad," he said. "When you play against a player like him, that he's able to return quick, hit a lot of good shots, then you are in big trouble. That's what happened."
With the second set secured, a relaxed Nadal got back in the groove, although a double fault sandwiched between two forehand errors saw him waste three match points in the final game.
He gave himself another chance on the next point when he kept an entertaining rally alive with a between the legs lob, and finished it off with a service winner.
Nadal, who hasn't dropped a set in three matches, next faces France's 24th-seeded Lucas Pouille, a 3-6, 7-5, 2-6, 7-5, 6-1 winner over Spain's 15th-seeded Roberto Bautista Agut.
Although his quarter of the draw has opened up with the early exit of Wimbledon finalist Milos Raonic, Nadal said any player he'll encounter from here on in will pose a serious threat, regardless of ranking.
Of his own world number five ranking, he said: "Sometimes I can play better than the number five, sometimes I can play much worse than the number five.
"And that happens the same with the other seeded players," he added. "We'll see what's coming the next couple of days."
Results from the fifth day of the 2016 US Open tennis championships at Flushing Meadows on Friday (x denotes seeded player):
Novak Djokovic (SRB x1) bt Mikhail Youzhny (RUS) 4-2 retired
Kyle Edmund (GBR) bt John Isner (USA x20) 6-4, 3-6, 6-2, 7-6 (7/5)
Jo-Wilfried Tsonga (FRA x9) bt Kevin Anderson (RSA x23) 6-3, 6-4, 7-6 (7/4)
Jack Sock (USA x26) bt Marin Cilic (CRO x7) 6-4, 6-3, 6-3
Rafael Nadal (ESP x4) bt Andrey Kuznetsov (RUS) 6-1, 6-4, 6-2
Lucas Pouille (FRA x24) bt Roberto Bautista (ESP x15) 3-6, 7-5, 2-6, 7-5, 6-1
Gael Monfils (FRA x10) bt Nicolas Almagro (ESP) 6-4, 6-2, 6-4
Marcos Baghdatis (CYP) bt Ryan Harrison (USA) 6-3, 7-6 (7/4), 1-6, 6-1
Madison Keys (USA x8) bt Naomi Osaka (JPN) 7-5, 4-6, 7-6 (7/3)
Caroline Wozniacki (DEN) bt Monica Niculescu (ROM) 6-3, 6-1
Johanna Konta (GBR x13) bt Belinda Bencic (SUI x24) 6-2, 6-1
Anastasija Sevastova (LAT) bt Kateryna Bondarenko (UKR) 6-4, 6-1
Roberta Vinci (ITA x7) bt Carina Witthoeft (GER) 6-0, 5-7, 6-3
Lesia Tsurenko (UKR) bt Dominika Cibulkova (SVK x12) 3-6, 6-3, 6-4
Petra Kvitova (CZE x14) bt Elina Svitolina (UKR x22) 6-3, 6-4
Angelique Kerber (GER x2) bt Cici Bellis (USA) 6-1, 6-1