PHILADELPHIA (AP) _ Andrei Chesnokov, his screams of pain echoing throughout the arena, broke his right leg Tuesday during a first-round loss to Todd Woodbridge at the Advanta Championships.

``I heard an enormous crack and I heard him screaming,'' Woodbridge said. ``Of course, I was on the other end of the court and I think he must have broken his ankle joint. It was horrible, a shock for me. I never saw anybody do that before.''

Chesnokov broke both the tibia and fibula in his lower leg and dislocated the ankle, according to tournament physician Dr. Brad Weiner and ATP Tour trainer Doug Spreen.

Weiner and Spreen attended to Chesnokov on the court, then set the ankle in the training room before an ambulance took him to Graduate Hospital, where he was scheduled to have surgery on the leg Wednesday.

``It's the worst injury I've seen in tennis,'' said Spreen, former trainer for the Cincinnati Reds. ``It's not a career-threatening type of injury, but I think he'll be out a minimum of four to six months.''

Woodbridge had won the first set and was leading 1-0 in the second set with the score 40-15 in the second game when Chesnokov chased the ball several yards behind the baseline and then suddenly toppled to the floor.

He lay on the court for several minutes, moaning. Chesnokov was then lifted off the court and carried out on the shoulders of several people.

Woodbridge, the No. 6 seed from Australia, drilled a passing shot down the right sideline that Chesnokov chased when he fell.

Chesnokov is one of the best players to come out of Russia. He has won seven titles in his career and was ranked as high as No. 9 in 1991.

Woodbridge will next face Byron Black of Zimbabwe, who defeated qualifier Richard Fromberg of Australia 6-4, 6-3. Fromberg double-faulted on match point in the second set.

In other matches Tuesday, South African Grant Stafford defeated Germany's Alex Radulescu 6-4, 6-2, and Patrick Rafter beat fellow Australian Mark Woodforde 6-2, 6-2.