World number two Rafael Nadal has moved to allay fears about his health following a dramatic press conference in New York.
The 25-year-old was discussing his victory over David Nalbandian with reporters when he suddenly called for his physio and slid off his chair in obvious pain.
After several minutes of treatment, the Spaniard left the room before returning later to conclude the press conference, where he announced that he was suffering from cramp.
"It's just bad luck that it happened in public. It was really hot, I ran a lot and you sweat a lot in these conditions," he told the Spanish press.
Nadal has been drawn against Luxembourg's Gilles Muller in round four.
Click here to see a video of the incident.
