Ullrich struggled in the shadow of Tour legend Lance Armstrong

Ullrich, 32, opted for the Swiss race over the Dauphine Libere event, which finishes on Sunday, because it ends closer to the 1 July start of the Tour.

"I've enjoyed success in this race in the past and feel at ease there," said the 1997 Tour de France winner.

"I live in Switzerland, so it's like I'm racing on home roads."

Ullrich, a long-time bridesmaid to seven-time winner Lance Armstrong in the Tour de France, came back from an injury-hit spring by riding for most of the three-week Giro d'Italia in May.

He won the time trial stage in Pontedera but pulled out with two days to go because of a back problem.

A good result is a key pointer to the Tour de France T-Mobile boss Rudy Pevenage

Ullrich, now fully recovered, will be backed by a powerful T-Mobile team, which includes world time trial champion Michael Rogers, expert climber Giuseppe Guerini and Andreas Kloden.

"A good result is a key pointer to the Tour de France," said team director Rudy Pevenage.

"We're sending a strong squad, with ambitions for a top overall placing. We won the Tour de Suisse in 2003 with Alexandre Vinokourov and in 2004 with Jan."

Ullrich triumphed in the 2004 Tour of Switzerland by one second after winning the final time trial stage to Lugano.

This year's race also ends with a similar 30km time trial around Bern on 18 June after about 1460km of racing.