The Spanish world number three will make his start at the Cincinnati Masters in the second round against one of a pair of qualifiers.
But after winning the Montreal title at the weekend to climb one notch higher in the rankings, Nadal is taking none of his success for granted.
"When you prepare your schedule, you don't know if you will play one match, two, three, four, or five. You can lose in the first round, so the schedule is changing a lot," he said.
"I do what I can. I don't want to be too smart and say I prepared the schedule great.
"That's why I arrived to Montreal in very good shape," said the player who returned to his winning ways after sitting out seven weeks following his first-round Wimbledon loss, conserving his fragile left knee under doctor's orders.
"I wanted to play on clay in the summer to be in rhythm and to have more chances to arrive more competitive to Montreal, but I didn't have that chance. But I arrived to Montreal with a good feeling and I was able to win.
"It's very difficult to say I found the right schedule. In our sport, the schedule changes a lot depending on the matches that you are winning or losing."
Nadal didn't start his 2013 season until February in South America and was unsure of what progress he might make after missing seven months with his knee problems following Wimbledon 2012.
His lightning return this season has surprised many - including himself and his team.
"After a long time not being allowed to do what you really want to do, you are able to come back with very, very fresh mentality knowing what you have to try to do to be competitive.
"I always thought during the seven months that I will work hard as much as I can to be back strong. Then you come back and you don't know how you will be."
As Nadal bids to win a second straight hardcourt Masters, top seed Novak Djokovic is taking aim at a record.
Should the Serb win the Cincinnati title after losing four finals here, he would become the first in the sport to claim titles at all nine Masters 1000 events over the course of a career.
Fifth seed Roger Federer is working on a return of his own after back pain last month forced him to miss Montreal and delayed his adaptation to a new larger racquet.
The Swiss won the trophy in Cincy a year ago and owns five titles at the event.
On court, Nadal's compatriot Feliciano Lopez began his week with an upset of Japanese 10th seed Kei Nishikori 6-4, 7-6 (7/4) while German number 11 Tommy Haas made up for an early exit a week ago in Canada by reaching the second round over South African Kevin Anderson 6-4, 6-4.
Russian veteran Nikolay Davydenko stopped Frenchman Benoit Paire 7-6 (10/8), 6-3 and Spaniard Tommy Robredo beat Brazil's Thomaz Bellucci 6-7 (6/8), 7-6 (9/7), 6-2.
In the women's draw, second seed Victoria Azarenka booked the first of the third round spots after a bye as she defeated American Vania King 6-1, 7-6 (8/6).
Azarenka was playing for the first time since losing the Carlsbad final to Samantha Stosur, then withdrawing injured from Toronto.
In the first round, Germans Mona Barthel and Andrea Petkovic got wins, with Barthel beating Lucie Safarova 6-3, 6-4 and Petkovic knocking out Daniela Hantuchova 2-6, 6-4, 6-1.