Lukaku tucked away Timo Werner’s cross at Brentford on Saturday, only to see the effort chalked out for offside.
Chelsea needed a wonderful Edouard Mendy performance to tiptoe away from the Brentford Community Stadium with a 1-0 win to step back to the Premier League summit.
Ben Chilwell’s sweet half-volley somehow settled the contest, while £98million club-record recruit Lukaku was again underused in attack.
Blues boss Tuchel has remained relaxed about Belgium hitman Lukaku’s recent barren run however, instead praising the 28-year-old’s selfless approach.
“I am not concerned as I felt him a bit tired, and then isolated because we were defending too deep as a block,” said Tuchel.
“I felt him a bit tired. Altogether we produced a very strong 60 to 75 minutes, including Romelu and Timo (Werner).
“Both of them, Romelu and Timo, were too far away to help us escape the pressure. That was the problem, but I have no concerns.
“Normally the best thing is that he scores but he is very unselfish at the moment, looking for Timo in good situations.
“And we had him in the situation (to score), it was a close offside decision.”
Chilwell’s second goal in as many league games proved decisive, the England full-back once again showcasing his impressive technical abilities.
The former Leicester star was forced out of Chelsea’s line-up for the opening few matches of the campaign, with Marcos Alonso preferred and in sparkling form.
Chilwell has since seized his chance and hit his straps in victories over first Southampton and now Brentford, leaving Tuchel suitably satisfied.
“I am very happy but it was necessary, We need everybody and especially a player like Ben in top shape but you can’t force things,” said Tuchel.
“I was honest with you guys, I felt he was tired and a bit mentally drained so it took time.
“He got his chance against Southampton and he took it. He was able to score and play for England which gave him more confidence and today again he was strong.
“He’s in good shape but we need him in this shape because we have many games in many competitions to play. I’m happy and it was a decisive goal that will give him confidence.”
Brentford besieged Chelsea’s goal in the final 20 minutes, with Mendy pulling off four stunning saves to thwart Thomas Frank’s rampaging hosts.
Midfielder Christian Norgaard executed a split-second overhead kick that would have left many goalkeepers motionless, only to peel himself off the turf and discover that Mendy had tipped the ball over the crossbar.
“You just see a chance of trying to hit it as high and quickly as possible,” Norgaard told Brentford’s official club website.
“But the keeper saw it well and made a great save.
“He was having a really good game and it was like he got bigger and bigger throughout the last 20 minutes of the game. But it will drop for us next time I’m sure.
“In the second half, I thought we were on top of the game. So I guess you could say one half each.
“We went toe-to-toe with one of the best teams in Europe, like we did against Liverpool, so a lot of confidence can be taken from the game.”
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