Chelsea facing benfica is not going to be an easy task for them if not for any reason but because Jose mourinho will be trying to prove a point. Benfica coach Bruno lage was sacked few days ago after a terrible defeat by qarabag and won't be willing to accommodate another lost in their next game against Chelsea in the coming days and secondly the presence of a new coach requires an excellent performance just to protect his new job at the club. Apart from providing protection to his job, the new coach Jose mourinho is a high profile coach with a lot of achievement in his coaching career, so finding the best way to win won't be a difficult one for him.
Benfica should be able to understand Jose Mourinho if in the end they were defeated by Chelsea because after all he had just been appointed as a coach and certainly needed time to manage the team to be better and directly facing Chelsea was of course a very tough challenge for Jose Mourinho even though Chelsea was his former club but Chelsea's performance had improved so Jose Mourinho no longer recognized the strategy used by Chelsea currently.
He's only been in charge for a short time and is facing a big match. He started the season with a draw against Rio Ave, a weaker team in the Portuguese league. This is a wake-up call for Benfica. They'll have to do much better if they want to win against Chelsea. This match will be a big test for Jose Mourinho.