If you watched the second half of the Brentford – Chelsea Premier League match, it look as if the old Barcelona squad or Bayern Munich hosted the Blues.The Bees were a dominant side and it was only the wonderful Edouard Mendy performance (and Ben Chilwell’s first half shot) that got Chelsea back to the Premier League summit.What frightens the supporters of the reigning Champions League holders is Romelu Lukaku’s recent club form. At Brentford Community Stadium on Saturday evening, the Belgian was again underused in attack – he did tuck away Timo Werner’s cross, but the effort got chalked out for offside. You don’t see this too often: Chelsea beat stubborn Bees in their first top-division clash since 1947Regardless of Lukaku failing to score, it is not something his manager is losing sleep over – even though this is the sixth match in a row for the Stamford Bridge club in which Lukaku did not find the back of the net.Blues boss Thomas Tuchel remains relaxed about Belgian’s recent barren run and is seeing the the silver lining in the 28-year-old’s selflessness.’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.’Wed, 20/10, 22.00: (1.13) CHELSEA (10.00) MALMO (23.00)Brentford occupied Chelsea’s goal in the second half, especially in the final 20 minutes, with Senegalese goalkeeper Mendy pulling off four stunning saves to thwart Thomas Frank’s rampaging hosts.Lukaku’s next chance to ‘break the lock’ for Chelsea presents itself on Wednesday evening, when Swedish side Malmo arrives to London as part of Champions League group stage round three.