Mauricio Pochettino says Tottenham have struggled to cope with the "mental challenges" of competing in both the Premier League and Champions League this season.
Spurs crashed out of Europe's primary club competition last night, succumbing to a 2-1 defeat against Monaco - their third loss in just five group games.
The north Londoners could now be destined for the Europa League, which will do little to lighten the club's rigorous workload.
But Pochettino is adamant that his players' failure to maintain their performance levels rather than a packed fixture list is the reason for Tottenham's demise.
"The challenge is not physical and tactical, it is to manage your mind, to play Saturday and Tuesday or Wednesday at a level like playing continuously in the Premier League," Pochettino insisted.
"We struggled to be ready to compete in every game. Monaco played on Friday and we played on Saturday night, in a 'final' against West Ham. To be ready again was difficult.
"It is not an excuse. We did not show enough quality. That doesn't mean we don' t have quality.
"But we need to improve our mentality. That's our challenge to be ready, everyone to be better," he added.
Tottenham's early exit has seen Pochettino's side receive a flurry of criticism for their lacklustre displays in European competition.
The Argentine coach named an unfamiliar side at Stade Louis II with Kyle Walker, Jan Vertonghen and Christian Eriksen all left on the bench.
But Pochettino has stressed that it was important for his squad to experience the level required to play in the Champions League.
"We are unbeaten in the Premier League. We are close to the top. To compete in the Champions League was tough. It is good for us to learn and try for the future. Our project is not finished yet.
"It is important to be calm in our analysis. It was a good challenge for us to compete in the Champions League and to show our real level," he added.
