Slot was discussing their superb start in today's match programme notes.
He declared: “Going by the league table as things stand, Chelsea are the strongest opponents we have faced so far.
“Going into this weekend, they were in fourth place having had a good start to the season and picking up some really good results along the way.
“This should not come as any surprise, of course. Chelsea have a lot of good players and they finished last season well also so it makes sense that they will continue to develop and improve and this is certainly happening right now.
“We have said repeatedly that there would be some big tests to come for us and this is definitely one of them.
“At the same time, it is also a big opportunity. Since we came together as a squad in pre-season, we have been developing ourselves; working incredibly hard to instil the methods that underpin the way that we want to play and challenging ourselves to become better in all areas of the game.
“That we have been able to keep on picking up results during this period is a real positive as it can only enhance our own belief in what we are doing and give us confidence to take forward, something that can only help in periods like the one we are now entering when the games against strong opponents come thick and fast.
“At the same time, we are aware that regardless of what the results or the current league table tell us, we also need to keep on improving. As a head coach, you are always looking for perfection even though you also know that perfection isn’t really attainable, but the reality right now is that we still have a lot of work to do.
“This is inevitable, of course. We are still only in our third month with the full squad together because so many of the players did not return until late July and early August due to their involvement in summer tournaments.
“As I said, the fact that we have picked up as many points as we have since then is very promising and it has given us a platform to build from in the coming weeks and months.”