Lukaku has become the first man ever to score in nine consecutive Europa League/UEFA Cup goals, beating Alan Shearer's eight.
“Records are records, but the victory was so important, Leverkusen are a team with great quality and an excellent coach. We made too many mistakes upfront, as we didn't finish the chances and could've won by more," Lukaku told Sky Sport Italia.
“The defence did a great job and in my view man of the match was Barella, as in recent weeks he has been just fantastic, he's everywhere."
There were so many wasted chances from Antonio Conte's men and odd scenes when the referee awarded them two penalties, only to revoke both decisions via VAR.
“We've been clearly improving recently, we just need to finish more of our chances and kill games off earlier. Now we have a week to prepare for the semi-final.
“That is going to be another huge game and we have to be ready."