Passion should have been a prerequisite for Tottenham Hotspur on their return to the Champions League after a five-year absence, especially with 85,000 fans packed into Wembley Stadium. So it was surprising to hear manager Mauricio Pochettino lament the lack of it from his players after a disheartening 2-1 home defeat by Ligue 1 leaders Monaco in their Group E opener. Tottenham's fans set a new club record attendance for a 'home' fixture -- flocking to the national stadium in their droves. But they left disappointed, probably wishing the match had been played at White Hart Lane. The decision to play at Wembley was forced on the club as their historic White Hart Lane stadium, soon to make way for a new ground next door, has a reduced capacity of around 31,000. Judging by Wednesday's lacklustre display in which Tottenham only shook off their apparent stage fright after goals by Bernardo Silva and Thomas Lemar put Monaco two ahead after 31 minutes, their Wembley stay may be shortlived. Pochettino, whose side's tenacity and energy saw them challenge for the Premier League last season before coming third, was deflated afterwards, and a little mystified. Monaco's manager Leonardo Jardim said his players had raised their game for the big stage and suggested the larger Wembley pitch had hindered Spurs. 'No that's not an excuse,' Pochettino, whose side beat Monaco 4-1 at White Hart Lane last season in the Europa League, told reporters. 'We conceded a goal after 15 minutes that is difficult to accept when you play for Tottenham. 'We needed to be more aggressive, more hungry and have more passion. We showed a lack of passion in the first half especially. It's shame because we fought so hard to be here and this was a big opportunity to give the fans a good victory. 'We were better than them, created more chances, had more possession. But Monaco were more effective.' The 85,011 crowd was a record for a British club at home in the Champions League, but the match lacked the intensity of Tottenham's memorable 2010-11 campaign when they won four of their five home fixtures to reach the last eight at the first time of asking. It was Tottenham's sixth match at the new Wembley and they have only won once -- the 2008 League Cup final against Chelsea. Switching grounds, it seems, is fraught with danger. Arsenal also struggled when they played their home Champions League matches at the old Wembley in 1997-98 and 1998-99 -- winning only two of six before abandoning the experiment. 'All players, especially good players, love to play in a stadium that is brim full,' Monaco's Jardim, who likened the win to his side's 3-1 victory over Arsenal at the Emirates Stadium in the last 16 in 2015, said. 'I think it helped us more than them.' Tottenham, who had chances to level on Wednesday after Toby Alderweireld halved the deficit, will hope for an improvement against CSKA Moscow and Bayer Leverkusen.