Former world No.1 Juan Carlos Ferrero has joined the coaching staff of rising German player Alexander Zverev, it was announced on Saturday.

Ferrero, 37, has started training with Zverev in the United States where Zverev is scheduled to play at the Washington event from July 31.

“Zverev is a different player, he is champion material. It is a new challenge that makes me happy so I want to do my best,” Ferrero said in a statement by his tennis academy in Spain.

Zverev, who won the Rome Masters two months ago and is ranked 11th, said on Instagram: “Welcome to the team JCF.”

Ferrero won the French Open in 2003 and was No.1 for few weeks later that year after reaching the US Open final.

He retired in 2012 and now runs the JCFerrero-Equelite