The Brazilian has been out for over a fortnight after damaging ankle ligaments in the 2-2 draw against Hannover earlier this month and the northern side lost 1-0 at home to Bochum without their influential winger last weekend.

That result saw them slip to fifth in the table, but Ze Roberto will not be able to help them bounce back against Mainz on Saturday and remains a doubt for the subsequent Europa League clash with Rapid Vienna and home league clash with Hoffenheim.

"I had to wear a plaster cast for 10 days and have lost some muscles and still have some pain," he said.

"There is no hope of me playing against Mainz. I will not return as only half a player; not as only Ze without the Roberto.

"I cannot predict when I will be back, but I believe I will still be able to play again this year."

The 35-year-old has followed Werder Bremen striker Claudio Pizarro, a former team-mate at Bayern Munich, back to the Bavarian city to receive treatment from the renowned doctor Hans-Wilhelm Muller-Wohlfahrt in a bid to speed up his recovery.

Meanwhile, Ze Roberto's team-mate Mladen Petric is optimistic his comeback will happen in 2009 - less than three months after undergoing surgery on a serious ankle injury.

"Straight after the operation, I was told January would be a realistic aim for a comeback, but I knew back then that it would happen before Christmas," he told the Hamburger Abendblatt newspaper.

"I am making good progress and am very hopeful."

The Croatia striker has stepped up his recovery this week, taking part in team training sessions alongside a personal fitness regime.

Since Hamburg have not won any of their last five matches, the sight of Petric and Ze Roberto back on the training field will come as a major fillip to coach Bruno Labbadia, whose side are facing a schedule of six games in 25 days.