Simone Zaza
Zaza is yet to score for the Hammers since arriving from Juventus. Getty

West Ham United have an obligation to buy Simone Zaza after 10 appearances for the club, according to the forward's agent and father.

Zaza joined the Hammers from Serie A champions Juventus days before the summer transfer window closed. The Premier League side paid an initial loan fee of €5m (£4.3m, $5.6m) for the Italy international with a permanent fee of €20m (£17.5m) to be automatically triggered after a certain number of games. Upon his signing, West Ham did not disclose after how many games that clause would be activated, but according to his representative, he is almost halfway there already.

Antonio Zaza told Tutto Juve: "He is on loan from Juventus with an obligation to buy after 10 appearances. I think he has four or five so far."

Zaza, 25, has started four games for Slaven Bilic's side this season, making a further appearance off the bench against Middlesbrough last Saturday.

The Italy international is yet to score for his new side and his father admits his son's start to life in east London has been "not good". Having made the move from Serie A to the Premier League, however, he stresses he still needs time to adapt to a new league and to Bilic's methods.

"He needs to settle, he has totally changed the way of playing. He is fine, you have to wait. There are no other problems. He is happy to be there. I repeat, they have another way of playing, it is not easy to settle in."

Zaza's slow start is unlikely to have been helped by West Ham's wretched start to the season. After seven games, they sit third from bottom having won one game, drawn one and lost five.

Following the international break, Bilic's side travel to south east London to take on Crystal Palace before hosting fellow strugglers Sunderland on 22 October.