BERLIN (AFP) - Former world number two Tommy Haas is doubtful for next month's French Open after pulling out of Munich's ATP event with a persistent shoulder injury just a few hours after defending champion Philipp Kohlschreiber withdrew.

It was a terrible Tuesday for Munich's organisers as the two players used on the tournament's advertising posters pulled out within hours of each other as third-seed Kohlschreiber and fifth-seed Haas left without playing a point.

After his first-round game against compatriot Michael Berrer was pushed back from Tuesday because of heavy rain in Bavaria, Haas was scheduled to be the first game on centre court on Wednesday morning.

But having struggled with a shoulder injury all year, Haas - who is now 36th in the ATP rankings - withdrew on Tuesday evening and said an appearance at the French Open at Roland Garros in late May is "doubtful".

"My shoulder is not up to it," said the 30-year-old former world number two on Tuesday.

"I have been having pain with it again and again."

Tournament director Patrik Kuehnen, Germany's Davis Cup captain, put on a brave face after two more doses of bad news following the weekend withdrawals of Thomas Berdych and French duo Jo-Wilfried Tsonga and Richard Gasquet.

"I feel sorry for the tennis fans," he said.

"The tournament has lost two of its biggest draw-cards today."

Kuehnen had been left stunned earlier in the day when defending champion Kohlschreiber withdrew with flu moments before he was due on court.

"I came here from Monte Carlo already with a slight cold, but it has taken a hold," said Kohlschreiber.

When play finally began on Tuesday afternoon after heavy rain had spoiled the day's schedule, Kohlschreiber's 11th-hour replacement Julio Silva from Brazil recovered from a nervous start to beat Bachinger 3-6, 6-2, 6-3.

Haas and Kohlschreiber aside, there were no real upsets on court with second seed Fernando Gonzalez from Chile beating Israeli Dudi Sela 6-3, 6-4, while Russian fourth seed Igor Andreev knocked out France's Gael Monfils 6-3, 6-4.

On Wednesday, top-seeded Frenchman Paul-Henri Mathieu will play Italy's Gianluca Naso in the second round and, having been given a wildcard, Russian Marat Safin is in action against Argentina's Carlos Berlocq in the first round.