Luiz was instrumental for Conte last season as Chelsea stormed to the Premier League title.
But the 30-year-old centre-back has struggled for form this season and appears to have fallen out with his manager in recent weeks.
Conte dropped Luiz from Chelsea’s
matchday squad tonight, with Andreas Christensen replacing him in the back line as the Blues beat Manchester United 1-0. The Italian claimed it was a tactical decision
before the game, but he has now told Luiz to step up his game if he is to save his Stamford Bridge career.
When asked if the Brazil international has a future at Chelsea, Conte replied: “I don’t know.
"He has to work really hard
otherwise they are on the bench or in the stand." Alvaro Morata’s second-half header secured the win for the Premier League champions, and Conte hailed his players’ desire and passion.
On the victory, Conte added: "It’s an important victory. When you play against Manchester United it’s always a massive game.
“We know very well this team is very strong.
This type of win is important for our confidence. We showed great desire and passion to win this kind of game.
“We can win or lose but our spirit must be
this.
“Last season our spirit was in every game –
we started this season with a lot of problems. We were up and down. This game showed if we want we can."