Chelsea boss Maurizio Sarri says he's been amazed by Slavia Prague's fitness levels.

The Blues will host Slavia for the second-leg of their Europa League quarterfinal tie this week.

Sarri said, "If we maintain the mentality of this level we can play right until the final.

"In Europe everyone thought we had a simple draw and but it is not so. I had never seen physical data like that from Slavia, they lead you to play draining games and something may have been missed here, but this is the Europa League."