Southampton manager Ronald Koeman has warned potential suitors that forward Sadio Mane will not be sold in January.

Premier League rivals Chelsea and Manchester United are believed to be monitoring Mane, who has impressed again this season.

After scoring 10 goals in his debut season for Southampton, the 23-year-old has managed six this term.

Koeman, though, insisted Southampton will reject any offers for the Senegal international.

"Rumours aren't important: we will sell nobody," Koeman said.

"You can ask again about Sadio, Man United, Chelsea, but we will sell nobody in January."

Koeman added: "The player is developing himself, with all the help from the technical staff and the rest of the players.

"But it's the reason why the team and the club is growing, and why we have 18 international players.

"They are showing qualities, and then of course big teams are interested. It's a normal progress of players who are developing themselves.

"In my opinion it's not about money, it's about ambition of players and people.

"Of course we don't play in the Champions League and we don't fight for the title, and that's a normal ambition for players to reach the highest level possible."