West Ham will allow Declan Rice to leave this summer if they receive an offer worth £120m from a Champions League club.
West Ham would also accept £100m plus a player for the midfielder, with the Hammers already receiving enquiries about him.
His most likely destination at the moment is Arsenal while Chelsea, Manchester United and Liverpool have also shown an interest in the England international.
Rice will have two years left on his contract this summer but West Ham have the option of extending it by another year. He rejected the offer of a new £200,000-a-week contract 18 months ago.
West Ham will only sell if the money is right and all proceeds from any potential sale would go towards strengthening the squad in the summer.
Out of respect for Rice and in recognition of his performances during six seasons in the first team, West Ham have promised they will not stand in the way of his dream of playing in the Champions League if a suitable offer is made.
Rice is believed to be earning about £70,000 a week and he would be expected to earn at least three times as much if he moves this summer.
West Ham value Rice so highly because they believe he is one of the best midfielders in the world, he has an excellent injury record and he is only 24.