Rafael Nadal recovered from a slow start, Venus Williams overcame a few glitches, and Justine Henin ran right into the next round Wednesday at a U.S. Open where the favorites kept rolling.

Nadal dropped the first six points of his match against no. 123 Alun Jones and later called out a trainer to check on his shaky knees.

The second-seeded Spaniard eventually hit his stride and, once again relying on his legs, moved into the second round 7-5, 3-6, 6-4, 6-1.

“I have to improve in the knees so much more if I’m going to continue in the tournament,” Nadal said.

Williams had some speed bumps – six double-faults, 20 unforced errors – in beating Ioana Raluca Olaru of Romania 6-4, 6-2.

After launching a Grand Slam-record 129 mph serve in her opening match, Williams reached a top speed of 124 mph and had to be content with only one ace. The two-time Open winner and current Wimbledon champ moved into the third round.

“I want to be the last one standing with a plate over my head,” Williams said. “I’m not stressed out on a few shots. Feel a little wiser.”

Henin also advanced into the third round, defeating Tsvetana Pironkova of Bulgaria 6-4, 6-0.

The top-seeded Belgian, bidding for her seventh major title, broke Pironkova’s spirit midway through the final set.

Caught close to the net, Henin raced back to the baseline, her legs churning at a full speed for a shot that won her the point. Pironkova flipped her racket in the air, then tried to catch it and missed.

“I know I have to work hard because I know a lot of surprises can happen, even if it looks easy,” Henin said. “You have to be careful all the time.”

Former Open champion Marat Safin, crowd pleaser Ana Ivanovic, no. 8 Tommy Robredo, no. 11 Mikhail Youzhny, no. 14 Elena Dementieva and no. 19 Sybille Bammer also won in straight sets.

“Hopefully, it’ll continue this way and keep it short,” Safin said after beating Frank Dancevic of Canada 7-5, 7-6 (5), 7-6 (7).

Roger Federer, Serena Williams, and Jelena Jankovic were scheduled later in the day. Tim Henman, playing his final Grand Slam event, was set to play his first-round match.

Ninth-ranked Daniela Hantuchova was the lone player in the upper echelon to lose. In all, it was an early breeze for those at the top.

A night earlier, Maria Sharapova and Andy Roddick overpowered their opponents. Former champions Lleyton Hewitt, Martina Hingis, and Svetlana Kuznetsova also won in straight sets.

The fifth-seeded Ivanovic defeated Aravane Rezai of France 6-3, 6-1. Popular on and off the court, her victory came a day after she received an unusual request from a fan.

“I was signing autographs after practice, the guy asked me to sign his forehead. I was like, are you kidding?” she said.

“I didn’t,” she said. “I felt bad for him walking with a sign. I say, ‘I can sign your ball or shirt, but forehead?'”

Robredo beat Bobby Reynolds 6-3, 7-6 (5), 6-1 and Youzhny defeated Nicolas Devilder of France 6-0, 6-1, 6-2. In the women’s draw, Dementieva beat Petra Cetkovska of the Czech Republic, 6-3, 6-2 and Bammer downed Meghann Shaughnessy 6-4, 6-3.

The highest-ranked player to lose was No. 28 Ai Sugiyama of Japan, beaten by Ekaterina Makarova of Russia 6-4, 4-6, 6-2. Also, No. 30 Potito Starace of Italy lost, defeated by Ernests Gulbis of Latvia 7-5, 7-6 (4).