SHANGHAI: Luckless Juan Martin Del Potro suffered his second Asian collapse Wednesday with the newly crowned US Open champion failing to finish his opening match at the Shanghai Masters.

The Argentine who was beaten by a qualifier a week ago in Tokyo in his first match since his career-defining grand slam title in New York, went down to Austrian Jurgen Melzer 7-5, 2-1, unable to continue.

In Tokyo, the 21-year-old had complained of feeling listless and unable to find his game. The symptoms were still there in Shanghai, his second and final date in Asia.

Top seed Rafael Nadal was hoping for a better start as the Spaniard began later in the second round against American James Blake.

Nadal needs to lift his game after losing badly in last week's Beijing semi-finals, winning just four games against Marin Cilic.

Sweden's Roland Garros finalist Robin Soderling bucked the losing trend as he reached the third round over Nicolas Almagro of Spain 6-4, 7-5.

Former Shanghai champion Lleyton Hewitt couldn't get past unpredictable Gael Monfils as the French 11th seed knocked out the Australian 4-6, 6-4, 6-2.

Hewitt, titleholder in the city in 2002, when he won the season-ending Masters Cup, threw away a 2-0 lead in the final set against Monfils, winner of the Metz title last month.

Hewitt dropped six straight games to go out as he played the French youngster for the first time in two years.

Hewitt, 28, who underwent hip surgery in the 2008 summer, refused to join this week's controversy over whether the length of the 11-month ATP season contributed to player injuries.

"We're all human and we're going to get injured at times -- no one is Superman out there," said the number 23, who was outside the Top 100 earlier this season.

"You can't keep putting your body through it all the time at these levels. But players know their bodies better than anyone, and especially the top guys. And the Tour needs the top guys," Hewitt said.

"The players shouldn't be obliged to play all the tournaments every week, because they know what it takes to be the best in the world."

Andy Roddick of the US, out of the event with a mysterious knee injury suffered during his first set against Swiss Stan Wawrinka, had been leading the debate over the lengthy season.

Roddick suggested that the only option not on the table for exasperated players to make their point was strike action.

He was joined in the verbal sparring with tennis powers by Spaniards Rafael Nadal and Tommy Robredo.

Hewitt called number one Roger Federer the master of scheduling to suit himself and his career. The Swiss has opted to miss the three-week Asian season, resting at home with his new family after saying he was exhausted.

Scot Andy Murray is out with a wrist injury, with his return date uncertain.

"That's something that Federer has been extremely good at. You shouldn't go out and try and make these guys play every week," said Hewitt, who is focusing his own season on January's Australian Open.

On Wednesday, two Germans made second-round exits as Robredo, the 14th seed, beat Florian Mayer 4-6, 7-6 (7/1), 6-4 while Rainer Schuettler advanced as compatriot Tommy Haas fell victim to a right shoulder injury after dropping the first set 6-4.

Madrid's Feliciano Lopez defeated Spanish 16th seed David Ferrer 4-6, 7-5, 6-1.

Czech Tomas Berdych drew fire from Marat Safin after a 3-6, 6-4, 6-4 loss, with the retiring Russian says his opponent had faked an injury.

"I was fooled by the great small shot he hit in the beginning of the second set where he pretended he was injured, and then all of a sudden he'll be running around and still playing normal," said Safin.

"It got me out of concentration, all of a sudden we start to run again. The third set just slipped away in the beginning. I came back but I lost track of the match. At four-all I didn't know how to play, how to find the game."

And the angry Safin had words for Berdych: "If you're losing, just be a man and lose as a man. Don't pretend that you are injured and then you start running around and start to hit winners.

"I mean, what kind of sportsman are you? What kind of man are you?"

Safin is on his last few weeks in the game, and is set to retire next month at Paris Bercy.