Rafael Nadal is not sure how his injured left knee will respond to his first hardcourt match of the year at the BNP Paribas Open.
Nadal is a two-time champion and three-time finalist at this event. He hasn't played a match on a hard court in almost a year and is only a month into his comeback from a left knee injury that sidelined him for seven months.
He has played three tournaments since returning, all on clay, and won titles in Brazil and Acapulco, Mexico, after losing to Horacio Zeballos in the final in Chile in his first week back.
"The results on clay were positive, especially because the knee was feeling better and better every week, especially last week," Nadal said. "Now I'm going to try here on hard (court). I don't know (what might happen). I cannot say much.
"I'm not confident about what I will be able to do here after one year of not playing on hard. I will try my best. I don't expect anything in results here."
His first match will be Saturday against American Ryan Harrison, who beat Go Soeda of Japan 6-0, 4-6, 6-3.
Down the road could be a quarterfinal round matchup with No. 2 Roger Federer and a semifinal match against No. 4 David Ferrer, whom Nadal beat 6-0, 6-2 in the Acapulco final.
For that to happen, it would take the same kind of improvement Nadal saw between his loss to Zeballos and his win over Ferrer.
"The difference is that I was able to compete close to 100 percent in Acapulco and I didn't have that chance in Chile," Nadal said while praising Zeballos for playing a fantastic match. "My tennis level was much better in Acapulco.
"You cannot expect to be back after seven months and play fantastic. You cannot expect to be back on hard court and practice 2 or 3 days and play a fantastic match in the first match.
"That's competition, that's the sport. You have to work to be 100 percent ready."
Two-time tournament champions Lleyton Hewitt and Daniela Hantuchova both won long first-round matches Thursday. Hewitt, who got his titles back-to-back in 2002 and 2003, beat Lukas Rosol of the Czech Republic, 6-4, 3-6, 6-1, and will face No. 15 seed John Isner on Saturday.
Hantuchova, the women's champion in 2002 and 2007, beat qualifier Stephanie Foretz Gacon of France, 6-3, 3-6, 6-4, in 2 hours and 12 minutes to set up a second-round match against reigning champion and top seed Victoria Azarenka.
In other women's first-round matches on Thursday, Taylor Townsend, a 16-year-old from Stonebridge, Ga., playing her fourth professional match of the year, beat 27-year-old Lucie Hradecka of the Czech Republic 3-6, 7-6 (1), 6-3, and 42-year-old Kimiko Date-Krumm of Japan was a 6-4, 3-6, 6-4 winner over Galena Voskoboeva of Kazakhstan.
American Jamie Hampton, who advanced to the fourth round last year at Indian Wells, is in the second round this time thanks to a 5-7, 6-3, 6-1 victory over Bethanie Mattek-Sands.
In the first night match of the 10-day tournament, Madison Keys beat Melanie Oudin, 6-4, 4-6, 6-3.
The men's first round started with David Nalbandian of Argentina beating Marcel Granollers of Spain 6-4, 6-2 and 20-year-old Bernard Tomic of Australia ousting Thomaz Bellucci of Brazil 6-4, 6-3.
Townsend said she "wasn't really nervous when I got on the court, but when I got up (ahead) I got really nervous. In the tiebreaker I was just trying to keep myself calm, so I wouldn't get ahead of myself.
"I've always thought that I belonged at this level, it's always been a dream of mine."