SHANGHAI, China -- Andre Agassi lost to Nikolay Davydenko, then pulled out of the Tennis Masters Cup less than an hour after second-ranked Rafael Nadal withdrew with an injured left foot.
Nadal withdrew Monday while Agassi was on court, losing 6-4, 6-2. The 19-year-old Spaniard had been due to face Gaston Gaudio in his opening round robin-match in the Gold Group.
Mariano Puerta became the fourth Argentine player in the draw when he was drafted to play compatriot Gaudio in Monday's later match at Qi Zhong Stadium.
Fernando Gonzalez of Chile will take Agassi's place in two remaining round-robin matches in the depleted Gold Group.
Top-ranked Roger Federer, also on the comeback from injury, leads the Red Group. He overcame Argentine David Nalbandian in his opening match Sunday.
Argentine Guillermo Coria and Ivan Ljubicic are in Federer's group.
Agassi lasted 1 hour, 14 minutes against Davydenko, then said he couldn't play the rest of his round-robin matches because he aggravated an injury in his left ankle.
"No chance for me to play again _ it's very dangerous and risky for my future," Agassi said. "This is an unfortunate setback."
Nadal said he had consulted local doctors in Shanghai and the tournament doctor, and all recommended he withdraw and rest the damaged ligaments in his foot.
Nadal said he hadn't been able to play or train since hurting the foot in his win over Ljubicic last month in Madrid.
"I had a lot of inflammation in the foot after Madrid," Nadal said. "After I came here, I had more pain."
The two latest injuries are a major setback for the season-ending Masters Cup, which is supposed to feature the top eight players of the year.