Jan Ullrich, the only German ever to win the Tour de France, was held on suspicion of assaulting a prostitute on Friday, as he returned to his native country seeking a fresh start to recover from drug and alcohol problems.
The former star was arrested within hours of arriving back in Germany on Friday. He had announced he was returning to Germany to begin treatment for drug and alcohol problems after his arrest in Spain last week on suspicion of breaking into the villa of a German film star and threatening his guests.
"I have a good gut feeling. This will be a fresh start," Mr Ullrich told Germany's Bild newspaper at his villa in Mallorca shortly before flying back to Germany by private plane. But he was back in a police cell on Friday after being arrested in the early hours of the morning at the five-star Villa Kennedy hotel in Frankfurt.
German police confirmed that a 44-year-old hotel guest had been arrested following a "physical confrontation".
"The guest had quarrelled with a woman escort who was staying with him, in the course of which he is suspected of physically attacking and injuring her," police said in a statement, adding that the alleged victim "had to undergo medical treatment for her injuries".
Prosecutors said Mr Ullrich did not present a flight risk and had been released on bail while inquiries continue. The incident comes a week after the former cycling star was arrested in Mallorca.
Mr Ullrich, who has a holiday villa on the island, was held by Spanish police after he allegedly broke into the garden of a neighbouring villa where the German actor and film producer, Til Schweiger was staying. Mr Schweiger was holding a party in the garden to celebrate the release of his new film Honey in the Head, and Mr Ullrich allegedly threatened the movie star and his friends.
"He went straight for a friend of mine with a broomstick," Mr Schweiger claimed to Bild am Sonntag newspaper. The two were previously friends but had fallen out over Mr Ullrich's drug and alcohol use, Mr Schweiger claimed. He later dropped the charges against Mr Ullrich.
"It was a big move from him," Mr UIllrich said at the time. "I'm very grateful to people like Lance Armstrong and Til Schweiger." Mr Armstrong, the disgraced former US cycling champion, has also sought to help Mr Ullrich overcome problems with drug and alcohol abuse.
Like Mr Armstrong, Mr Ullrich's cycling legacy has been tarnished after he admitted to using blood doping. He became the only German to win the Tour de France in 1997 and won gold and silver Olympic medals for cycling events in 2000.
But in 2006 he was banned from the Tour de France on suspicion of doping, and the following year he retired from competitive cycling.
In 2013 he finally admitted to using blood doping but unlike Mr Armstrong refused to return his Olympic medals.
"Almost everyone at the time was taking performance-enhancing substances. I didn't take anything that was not taken by the others," he said in an interview with Sky Sports at the time. "It would only have been cheating for me if I had gotten an advantage which was not the case. I just wanted to ensure I had an equal opportunity."
Mr Ullrich's 13-year marriage recently broke down, and a few days ago he told reporters he had decided to undergo treatment for his drug and alcohol problems for the sake of his three young children, who he has not seen since Easter.
"I hope when he gets out of jail he cleans himself up and returns to the person he actually is, namely a kind-hearted, lovable, generous man, who adores his children and his wife," Mr Schweiger said following Mr Ullrich's arrest in Spain.