Roger Federer says organisers of the Shanghai Masters are right to criticise the spate of player withdrawals which are threatening to devalue the event.
Agassi (L) and Nadal both pulled out of the Masters Cup while in Shanghai
Chiefs of the showpiece event spoke out after Andre Agassi joined Andy Roddick, Marat Safin, Lleyton Hewitt and Rafael Nadal on the sidelines.
"I think criticism is allowed at this point," said the world number one.
"I understand the big disappointment from the government, from the tournament and from the fans."
Agassi became the latest player to pull out of the Masters Cup on Monday with an ankle injury after losing tamely in his first match against Nikolay Davydenko.
Only an hour earlier, French Open champion Nadal withdrew with an ankle injury.
"I don't appreciate what Agassi is doing. He made the announcement without telling anyone," said organising committee deputy director Wang Liqun.
In 2000, when Agassi came for the Heineken Open, he took an early exit in the first round. "Two years later in the Masters Cup, after two defeats, he cited a hip injury and took off. This year it happened again."
Federer himself arrived in Shanghai nursing an ankle injury after hurting his ankle in practice.
But the Swiss Wimbledon and US Open champion took the court undeterred and has won both of this matches against David Nalbandian and Ivan Ljubicic.
"I sort of arrived basically on one leg," said Federer. "Now that I can play it's fantastic.
"It should also show a message how important this tournament is to tennis. For me this equals a grand slam."
The high-profile withdrawals have sparked a debate about player burn-out with Agassi calling for a changes to the event schedule.
And Masters Cup deputy director Qin Weichang has urged the ATP to trim its crowded calendar.
"We are suggesting that they really need to make some adjustment for the athletes' interest," said Qin.
"When they don't have an injury, they will perform better."
And Federer agreed Agassi did show great commitment by at least trying to play through injury in Shanghai.
"I think it's still great that he shows up and tried," said Federer.
"Maybe the other guys could have tried to. But I don't think so because they know their bodies."
Nadal pulled out before his opening match with a foot injury, Roddick has an ongoing back problem, Safin has a knee injury and Hewitt is awaiting the birth of his first child.
Sweden's Thomas Johansson is the latest player to be drafted in as cover. Argentina's Mariano Puerta and Chile's Fernando Gonzalez have already stepped in.