Tottenham manager Mauricio Pochettino admitted that his side were far from their best in the 3-0 defeat to Borussia Dortmund in the Europa League on Thursday.
Pierre-Emerick Aubameyang's opener on the half-hour mark was followed by a second-half brace from Marco Reus as BVB put Spurs to the sword in the first leg of their tie at Signal Iduna Park.
"It was a bad day and we're very disappointed," the Argentine coach said after the match. "We didn't play well. This can happen in football.
"They were better but I'm disappointed because we didn't play in the way we normally play. There are always many circumstances.
"In front of us we have a very good team who would normally play in the Champions League, not the Europa League. That is their level.
"We can take some positives like good experience but I'm disappointed with the result because it's never good to lose 3-0. We will give our best in the return leg, it's difficult but we will try."
Spurs resume their Premier League title race against rock-bottom Aston Villa on Sunday, before hosting Dortmund for the return leg at White Hart Lane next Thursday.