After going down 2-1 to Young Boys on Monday, Sam Allardyce's team were beaten by the same scoreline against Swiss champions FC Basel.
Young winger Stanislas tucked away a penalty after Olly Lee was brought down in the area, but Basel grabbed their winner from the spot late on after a foul by Julien Faubert.
Carlton Cole got a run-out as a late substitute despite the club agreeing a fee with Stoke for his services while Kevin Nolan made his first appearance since joining from Newcastle, but there was no place for England midfielder Scott Parker.
Assistant manager Neil McDonald said: "We've played one team who'll be in the Europa League and one who will be in the Champions League and they're five weeks ahead of us.
"I think the players have acquitted themselves really, really well."