Slaven Bilic admits West Ham may have to offer Dimitri Payet an improved contract to ensure they keep him at the club.
French playmaker Payet is only seven months into a five-year deal following his £10.75million summer switch from Marseille.
But such has been the 28-year-old's impact at Upton Park, Bilic knows he will have admirers among Europe's elite.
"The club is moving, with the new stadium and everything, and the most important move is to keep your best players," said Bilic.
"Dimitri Payet is our best player. And of course I would love to have him happy, long-term, at the club.
"He only signed a few months ago, but he has made a huge impact and while he has a long contract he is in a good position.
"We all want to keep him for a long, long time."
Payet has scored six goals and helped create plenty more this season, although he was not at his best during last week's win over Aston Villa or Saturday's 1-0 defeat at Southampton.
But Bilic, who has compared the midfielder to Arsenal's Mesut Ozil, insists people cannot expect miracles from him every week.
"It's hard if you set yourself a standard, like the second half against Bournemouth when he scored a great free-kick and made a brilliant assist," added the Hammers boss.
"I can't expect from him every week to score goals and make some great things.
"Ozil? He did it at the weekend but two weeks ago he didn't. Those positions are the most difficult ones. Did David Silva do it at the weekend? No, he didn't. Is he dropped? No, he's a great player."
Payet is expected to start Tuesday's FA Cup fourth-round replay against Liverpool but defender James Tomkins is out with a calf injury.
Source: PA
