Thomas Tuchel substituted Romelu Lukaku because he looked "tired and isolated" in the 1-0 victory against Brentford, as question marks continue to linger over the best way to utilise the Belgian forward.
The 28-year-old did have a goal ruled out for offside during the Blues' trip to the Brentford Community Stadium, but he looked largely out of sorts for much of the game and didn't really have an impact on proceedings.
He was hooked on 77 minutes in favour of Kai Havertz, and Tuchel admitted after the game that Lukaku's substitution was due to the forward looking 'tired and isolated' alongside an equally ineffective Timo Werner. But the German tactician did try and reassure supporters, suggesting there should be 'no concerns' over the striker's inability to get on the scoresheet.
"I felt him a bit tired today," Tuchel said. "Altogether we did a very strong 60 to 75 minutes, including Romelu and Timo. I am not concerned as I felt him a bit tired and then isolated because we were defending as a block too deep.
"Both of them, Timo and Romelu, were too far away to help us and escape the pressure. That was the problem today. But I have no concerns.
"Normally, the best thing is he scores but he is very unselfish at the moment, looking for Timo in good situations, and when we had him in the situation it was a close offside decision."
Ben Chilwell was the hero for Chelsea, slamming home on the stroke of half-time to clinch all three points for the European champions. The Bees did not make it easy for the Blues, however, who had to rely on some miraculous heroics from goalkeeper Edouard Mendy.
Chelsea's inability to kill the game and create more chances from open play could become an issue later down the line, and Tuchel will be hopeful that Lukaku can recapture his form of the past two seasons to reignite their attack.
The former Inter striker starred in Serie A, scoring 47 goals across two campaigns to help I Nerazzurri end a decade of Juventus dominance and clinch an unexpected scudetto in his final year at the club.