West Ham chief David Sullivan believes Javier Hernandez could be the club's greatest ever signing.

Former Manchester United and Real Madrid hitman Hernandez has just arrived from Bayer Leverkusen.

"I think he is potentially the best player who has ever come to the club," Sullivan told talkSPORT.

"In recent years, he is probably the best proven goalscorer we have signed since we have been at the club.

"He's done it in the Premier League with Manchester United. We were lucky he only had a year left on his contract with his club and that allows you to negotiate a deal.

"We tried very hard to get him two years ago but unfortunately he chose the German club ahead of us."