Spurs came from two goals down to draw their Europa League quarter-final first leg 2-2 against the Swiss side and will have it all to do after a disappointing performance.
Friedel revealed that manager Andre Villas-Boas was unimpressed with the first-half display but the veteran United States international feels that a semi-final place is still within reach.
"When you're down 2-0, to come back, we can take a little bit of encouragement from that," Friedel told ITV.
"But we didn't start the game well, we know that and the gaffer had some words at half-time.
"It will be tough out there, but we've got a lot of quality in our squad."
The most worrying news of the night was a serious-looking injury to Gareth Bale, who went over on his ankle close to the end.
"I didn't get a good view of Gareth's (injury)," Friedel added.