Pavel Vrba admits his Sparta Prague side have a lot of improving to do if they're to get the better of Rangers on Thursday.
The Czech side sit four points off the top of the league and drew their opening Europa League game with Brondby.
Though a reserve team got the better of minnows Lisen in the cup in midweek there has been criticism after the draw with Jablonec last weekend.
Saturday evening sees Sparta take on Zlin before attention turns to their European campaign.
It's a huge week for the capital club, who then welcome Rangers to Letna before facing arch-rivals Slavia Prague in the derby.
And Vrba admits his side will need to be at their very best to get through two of the biggest matches of their season.
He said: "I don't think we have a major problem, but it's true that I expect more from some of my players. For example, David Karlsson and Adam Karabec weren't at their best, but neither were fully fit.
"We have a very important week and we know Rangers will present us with a significant challenge that is higher than most of our league opponents.
"We were criticised for only drawing at Brondby, but although we didn't play particularly well, I thought that was a good result because other teams will struggle there too.
"But I accept our draw against Jablonec wasn't a good performance and we need to improve for what is a vital few games for the club."
