Javier Hernandez may be West Ham's best-ever signing - David Sullivan

West Ham joint chairman David Sullivan has told talkSPORT he believes new signing Javier "Chicharito" Hernandez could be the best player ever to join the club.

Hernandez completed a move from Bayer Leverkusen on Monday, with the striker -- who spent five years on the books at Manchester United -- entering the final year of his contract with the Bundesliga club.

The clubs confirmed last week that a deal had been agreed and the 29-year-old has signed a three-year contract.

Hernandez scored 59 goals in 157 appearances for United before moving to Leverkusen, where he netted 39 times in 76 games.

And Sullivan said: "I think he is potentially the best player who has ever come to the club.

"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."

Hernandez becomes West Ham's fourth signing of the summer following the arrivals of Marko Arnautovic on a club-record fee from Stoke, Pablo Zabaleta on a free transfer and Joe Hart on loan from Manchester City.

And Sullivan said Slaven Bilic's side would be targeting trophies after a tough campaign last season.

He added: "I realise the supporters say we won't do this and that, but we start the season in three [competitions] and the ambition is to win those three trophies.

"I know it is very, very unlikely we will do that -- and any one of them would please the board -- but you have to think you can win anything, and on our day we can beat anybody.

"Leicester was something we all thought could not happen, but they showed it can happen. I'd settle to win a cup... I'd love to go to Wembley and win a cup."