NEW YORK - Rafael Nadal has no way of knowing how his aching stomach muscles will feel when he plays in the U.S. Open semifinals.
And no one else knows exactly how much Nadal is bothered by the injury, because he steadfastly refuses to delve into details.
What the six-time major champion is willing to make clear: He feels a lot less drained these days than he normally does by the time the year's last Grand Slam tournament - the only one he hasn't won - rolls around.
"I'm more fresh than last year. We will see how I am physically (today). But mentally - last year, (I) was totally destroyed mentally," Nadal said Saturday after completing his rain-interrupted quarterfinal with a 7-6 (7-4), 7-6 (7-2), 6-0 win over error-prone Fernando Gonzalez. "Mentally, this year, I am perfect, no?"
In a women's semifinal, unseeded Kim Clijsters beat No. 2 Serena Williams 6-4, 7-5.
The No. 3 seed Nadal beat No. 11 Gonzalez in a match that began Thursday evening, was suspended that night because of showers in the second-set tiebreaker and didn't resume until Saturday because of more rain Friday.
At a news conference, tournament director Jim Curley and U.S. Tennis Association executive director Gordon Smith declined to commit to building a retractable roof over Arthur Ashe Stadium, a topic of much discussion around these parts.
"It will be some time before there's any decision made on whether or not to go forward with the roof," Smith said.
Not long after Nadal-Gonzalez ended, a steady drizzle returned, forcing the postponement of the men's doubles final and delaying the start of the women's semifinals. Those semis - Williams vs. Clijsters and Caroline Wozniacki vs. Yanina Wickmayer - finally began around 9:30 Saturday night.
Weather permitting - two key words at Flushing Meadows lately - Nadal faces No. 6 Juan Martin del Potro in one men's semifinal today, and No. 1 Roger Federer meets No. 4 Novak Djokovic in the other. The final, usually played on Sunday, has been pushed back to Monday on account of the weather for the second consecutive year.
Gonzalez, for one, figures this year's championship matchup is a foregone conclusion.
"You always expect that Federer plays the finals against Nadal," Gonzalez said. "Good for the game. It's good for the fans."
Del Potro beat Nadal the past two times they played. Plus, the 6-foot-6 Argentine should be well-rested, considering that he hasn't played a point since his quarterfinal victory Thursday. Federer, seeking a sixth consecutive U.S. Open championship, and Djokovic, the 2007 runnerup, have been able to enjoy some rest since winning their quarterfinals Wednesday.
Nadal, not so much.
He and Gonzalez first stepped oncourt Thursday at about 7 p.m. After Nadal won the first set, he took a medical timeout to have a trainer check his abdominal muscles.
Four games into the second set, there was a 75-minute rain delay. After play resumed, Nadal took a 3-2 lead in the second tiebreaker when they were forced off the court for the night.
Not until about 37-1/2 hours later did they pick up again.