Tottenham manager Mauricio Pochettino admitted his side were not matching the standards they set last season after a humiliating defeat to Bayern Munich in the Champions League.
Last year's runners-up were thrashed 7-2 on their own patch to leave them bottom of Group B with just one point from two games.
Asked by RTÉ soccer correspondent Tony O'Donoghue whether the team had declined, the Argentinian admitted: "That is the feeling. We need to do more.
"After getting to the final, it's not easy to keep the level that we showed last season."
Pochettino was bewildered by the manner of Spurs' collapse after taking an early lead and outplaying the visitors in the opening stages.
Bayern led 2-1 by the break however and former Arsenal man Serge Gnabry scored four goals in the second half.
"The first 30 minutes we played really really well. We played one of the best periods that I remember in the last few years.
"we created a lot chances, we defended well, we were very aggressive. We deserved to score maybe one or two more goals but we didn't.
"They were very clinical and in the second half, every single touch near goal they scored.
"When that happens you need to accept that and be strong. Of course, disappointed, because the feeling is that you play well but you lose the game 7-2."
Spurs looked tired after playing with 10 men for an hour in Saturday's Premier League victory over Southampton but Pochettino said Bayern had simply taken their chances better.
"It was a great effort against Southampton, 10 men against 11. That's not an excuse, we started the game really well but it was hard to keep that effort during 90 minutes.
"But more than this, they were very clinical. I think had 11 shots on target and more than 70% were goals."
As to whether thoughts were already turning to January reinforcements, Pochettino laughed off the suggestions.
"It's so early. I think we need to work harder and make a big effort."