Rayo Vallecano winger Bebe said he thought it might have been a "joke" when he first heard he was moving to Manchester United.
Bebe made a shock move from Vitoria Guimares to United in August 2010 in a deal reported to be worth £7.4 million but failed to make an impact at Old Trafford.
After making just two senior appearances for United, he had loan spells at Turkish side Besiktas and Portuguese clubs Rio Ave and Pacos de Ferreira before leaving Old Trafford permanently to join Benfica in July 2014.
The 25-year-old, who is currently impressing during a loan spell at Madrid-based La Liga side Rayo, told AS in an interview that he had been surprised when he heard he was moving to United.
"It all happened very quickly, it was a surprise," Bebe said. "One day I was training [in Portugal] and immediately they told me to leave, that I was going to sign a five-year contract. I didn't know if it was a joke. I was not there long, but I made the most of it."
Bebe, who spent time living in care and at a homeless shelter during his teens, said his big-money move was difficult to take in.
"It was the dream of many kids -- it seemed crazy," he said. "When I arrived there I was with the best players in the world. I found it a bit difficult; the first week I was breathing deeply. I got used to it though."
He said Rio Ferdinand, Wayne Rooney and Ryan Giggs had been the United players he was most impressed by at first, adding: "A few months before I was watching them on the TV and soon I was running, jumping, talking with them.
"I watched Giggs a lot, saw how they asked him for photos, autographs, shirts ..."
Having faded from view during the years after he moved to England, Bebe did come back to prominence when on loan from Benfica at Cordoba during the second half of the 2014-15 campaign.
He has continued his good form as a regular starter with Rayo this term, contributing two assists and a goal in his last six La Liga games.
He said he would be better prepared now should his future hold another move to a bigger club.
"I arrived there [at United] without much football education, with what I had -- talent, pace, strength -- but I was lacking many things," Bebe said. "If a big club signed me now, it would be different."