Antonio Conte has warned David Luiz he faces a fight to win back his Chelsea place after the Brazil defender was dropped for the 1-0 win over Manchester United.
Luiz paid the price for some sloppy performances as Chelsea manager Conte left him out of the squad at Stamford Bridge on Sunday.
The former Paris Saint-Germain player, one of the key members in Chelsea's title triumph last term, watched from the stands as Andreas Christensen, Cesar Azpilicueta and Gary Cahill filled the central defensive positions for the champions.
That trio easily kept United striker Romelu Lukaku and his teammates at bay as Alvaro Morata's 55th minute header sealed a vital victory.
Conte had been prompted to ditch Luiz following the midweek Uefa Champions League loss at Roma.
But, having told an television interviewer after the United game that he didn't know if the defender had a future at Chelsea, when he faced the written press, he only told Luiz he wouldn't be granted an immediate recall.
"It's very simple, the coach has to make the best decision for the team. Tonight the best decision was to play [Andreas] Christensen and have [Ethan] Ampadu on the bench," Conte said.
"I decided this way tonight, maybe I can decide a different way in the future or I can continue the same way."
Conte's decision to axe Luiz was as much a warning to the rest of the squad to improve their performances as an individual attack on the centre-back.
The Italian's message was received as Chelsea gave a commanding performance to secure their third successive league win and stay within nine points of leaders Manchester City.
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"I must take the best decision for the club, not a single player. It is only a tactical decision. It's normal," Conte said.
"This can happen to every one of my players if I see they are not in good form. I have to make important decisions."
Conte's own future had been in question last week after demanding owner Roman Abramovich made one of his infrequent visits to the club's training ground.
Reportedly struggling to stop his players complaining about his intense training regime, Conte badly needed a restorative victory and he was relieved to see Chelsea respond to his demands for more intensity.
"We played with great energy and great passion. I saw a lot of positive things," he said.
"They decided they would fight. My players had the will to help each other.
"For many reasons we started this season with a lot of problems, the confidence can go down.
"To see this spirit, for sure I'm pleased. If there is this passion, we can fight for something important."
Conte couldn't resist taking a swipe at United manager Jose Mourinho, who had mocked the Italian's complaints about injuries earlier this season.
Mourinho mentioned injuries to the likes of Paul Pogba as a reason why United slumped to their second defeat in their last three league games.
But Conte said: "When you have 24 players in the squad, if you have one or two injuries that doesn't work."
It was another chastening return to the Bridge for Mourinho, who has been beaten on all three of his visits to his old club since taking charge at United last term.
But although United trail eight points behind City, Mourinho refused to surrender the title to Pep Guardiola's side.
"We are worried but eight points in the Premier League is not the same as eight points in La Liga or the Bundesliga," he said.
"There is still a lot to play. I hope in the busy period of late November, December, we are going to be at maximum strength with Pogba and [Zlatan] Ibrahimovic back."
Mourinho also defended Lukaku after the United striker gave the latest in a series of anonymous displays.
The Belgian has now gone seven games without a goal, but Mourinho said: "I'm not interested in stats. I'm happy with his attitude. He had a chance with a good shot and created space for others."