Maurizio Sarri says it is "impossible" for Eden Hazard to leave Chelsea even though the transfer market remains open across Europe.
Hazard has been heavily linked with Real Madrid after performing superbly for Belgium at the World Cup, Los Blancos having already raided Stamford Bridge for goalkeeper Thibaut Courtois.
The Premier League transfer window closed on Thursday with Chelsea having kept hold of their star forward, however other clubs in Europe are still able to buy players.
Madrid have until August 31 to conclude their transfer dealings and Courtois expressed his desire for Hazard to join him at the Santiago Bernabéu at his presentation in the Spanish capital.
However, Sarri insists that will not happen given Chelsea would have no opportunity to replace the 27-year-old.
"Hazard is with us, I have spoken with him three or four times and he never said anything about the market, he is very happy to stay here," the Italian told a media conference on Friday.
"It [Hazard's departure] is impossible, here the market is closed so we cannot change important players now, so it's impossible."
Chelsea's attempt to tie Hazard down to a new deal at Stamford Bridge to ward off the attentions of Madrid continues to drag on, but Sarri believes the forward would be keen to agree an extension.
He added: "I don't want to discuss contracts, it's not my job.
"My job is to improve the players, to try and win matches, not to sign new contracts.
"But I have seen a player [Hazard] very happy to stay here so I think it [the new contract] will be no problem."
While Sarri expects Hazard to say there could be others leaving Chelsea in the coming weeks – including Tiemoue Bakayoko - as the former Napoli boss looks to trim his squad.
"The squad is too large, so I think some players have to go on loan," said Sarri. "But I don't know who at the moment.
"I prefer to have 23, 24 players and three or four very young players, no more. Maybe [Bakayoko], I don't know in this moment, you would have to ask the club."