Chelsea coach Bolo Zenden says they won't take Europa League opponents Sparta Prague.
Chelsea are still strong favourites to progress over two legs but Zenden has warned his players not to take victory for granted.
He said: "They've been in a winter break, so they had a month to prepare for this game. They will be up for it and be ready physically.
"The good thing is it's a two-legged game. It is always important to score away in Europe. I expect them to be quite good because they have had very good results, which is how they have come to this stage in the competition."