Slaven Bilic has compared misfiring West Ham striker Simone Zaza with Arsenal and Netherlands great Dennis Bergkamp.
The Italy international - who joined on loan from Juventus in August - has made an uninspiring start to his Hammers career, failing to score in four matches.
But Bilic cited the example of Bergkamp, who initially struggled to settle in England after arriving from Inter, but went on to become a talismanic figure for the Gunners.
"He is definitely a good player who came from a big club to a new country," said Bilic, whose side sit 18th in the Premier League and host Middlesbrough on Saturday.
"New players need time. If we go back and think about Dennis Bergkamp, who needed - I don't know - a year?
"It is quite common with even the best players from abroad. Plus, Zaza wasn't a regular there [Juventus] and didn't have match fitness.
"It takes time sometimes and unfortunately we don't have that time."
The London club, who paid a EUR5million loan fee for Zaza's services, can make the move permanent for EUR20m at the end of the season.