London - Goalkeeper Victor Valdes said on Friday he hadjoined Manchester United "to win trophies."
The Spain international, whose contract with Barcelona expired last summer, signed an 18-month deal with United, with the option of an extra year.
Valdes has not played since undergoing knee surgery in March and will be number two to compatriot David de Gea.
"When you have won the most important trophies in football, it's like a drug," said Valdes, who described De Gea as "the best goalkeeper in the world.
"You want to win again and you feel these amazing moments with your fans...with your family and with your teammates," he told United's website. "It's very nice and my ambition is to win every game and every trophy."
United manager Louis van Gaal, who worked with Valdes when he was at Barcelona several years ago, said the 32-year-old would provide competition to De Gea.
"Victor is a very experienced goalkeeper and his record speaks for itself," the Dutchman said.
"Victor has remained very professional throughout his rehabilitation from injury and has been very impressive during his training sessions with the first team over the past weeks.
"He joins the club as the number two goalkeeper and is a great addition to the first team."
Valdes said he would be patient and wait for his opportunity at United who are currently placed third in the league, nine points behind joint leaders Chelsea and Manchester United.
"I am here to help everybody," he said. "I am a part of the team and I am not a problem, I am just a part of the team.
"If I play a game, I am always thinking about playing well and to help the other teammates, to help them to win the match."