Sparta Prague goalkeeper Tomas Vaclik is convinced they can upset Europa League opponents Chelsea.

Sparta host Chelsea, last season's Champions League winners, in the first leg of the Europa League last-32 in their first competitive fixture since December 6.

"I believe we will add one more match to that run and travel to London with a result that keeps our chances alive," Vaclik said.

"To succeed, we'll have to play our best football. Even if Chelsea are not having their best period right now, they have the winning mentality of a big club and self-confidence."