Eddie Howe says there is no way he would contemplate letting defensive midfielder Bruno Guimaraes leave Newcastle United for Real Madrid.
The Brazil international, 24, has recently been linked with a move to the La Liga and European champions, who see him as a potential replacement for Manchester United target Casemiro.
Guimaraes arrived in January from Lyon for £35m with £6.6m in add-ons.
Howe said he was building a team to be successful “over the next few years”.
He added: “We want to build that squad and enhance the group, not take away our best players.”
Spanish publication AS reports that sources close to Newcastle have stated the club would ask for double the transfer fee that was paid to French side Lyon seven months ago.
Manchester United are closing in on the signing of Guimaraes’ fellow Brazilian Casemiro and the club are optimistic the deal will be completed in the next few days.
Guimaraes has become a fans’ favourite at St James’ Park after the club’s new owners spent big in the January transfer window.
“That was an incredible piece of business, really,” said Howe. “Not just as the footballer as well, you’ve got to consider the person.
“The person is a brilliant lad who came here when the club was in a relegation battle – you have to remember this – with no conditions, no way, out, no escape clause and wanted to fight to keep the club in the Premier League.”
Newcastle have four points from their opening two Premier League games after beating Nottingham Forest and drawing with Brighton. They face leaders Manchester City on Sunday.