Feb.6 (GMM) Ralf Schumacher is this week back in action for Mercedes-Benz, increasing the likelihood that the former grand prix winner will race in the German touring car series (DTM) in 2008.

According to publications including Cologne's Express and the German national Bild, the 32-year-old's latest three-day run at the Estoril circuit, concluding on Thursday in Portugal, was intended to be secret.

Schumacher's first run in the black C-Class was in mid January.

Express said an announcement about Ralf's plans for 2008 could be made later this month.

To Bild, he would not confirm that he has already decided to contest the series in 2008, after failing to retain his Toyota F1 seat.

"I don't want to say anything, but I would not be here if I did not find the driving a lot of fun," Schumacher said.

"If we do cooperate, I will be in a 2007 car. This is my own desire, in order to get used to everything. And now I want to use every minute in order to get to know the machine."

Mercedes' competition director Norbert Haug agrees.

"No-one should expect any miracles from him, because formula one and DTM are two very different pairs of shoes," the German said.