Vaclav Prochazka’s goal gave Viktoria Plzen a 1-0 win over Atletico Madrid to snatch top spot in Group B.
With Diego Simeone's side already through to the knockout stages, the Argentine Coach named a side mixed with youth and experience.
That blend stuttered in the early stages though, and went behind on 26 minutes as Prochazka finished off a Michal Duris corner.
Adrian Lopez and Diego Costa went close before the break, but good saves from Matus Kozacik saw Atleti go into the interval a goal down.
After half-time, the capital club started to show their class, and really should have bagged an equaliser, first through Koke and then Diego Costa again.
Things got worse for the Brazilian forward as he was given a straight red card in the last minute and the Rojiblancos went down to their second defeat of this Europa League campaign.