Manchester United coach Ruben Amorim has explained why the UEFA Europa League is harder than the Champions League.
The Red Devils played to a 1-1 draw against Real Sociedad in the first leg of their round of 16 on Thursday evening.
Read: Man Utd left frustrated in Europa League tie
United will be back in action on Sunday evening against Arsenal, who were involved in Champions League action on Tuesday at PSV Eindhoven.
The Portuguese tactician believes the Europa League is tougher due their being not enough time to recover for the weekend fixtures compared to the teams competing in the Champions League.
"We need to survive Sunday. The team was so tired in the last 20 minutes," Amorim said, as per Goal.
"I think the biggest problem is to not have all of the players because, in the beginning, people talk about our rotation - especially in Europe, we are changing all the time.
"It's because of this, because it's really hard, and the Europa League is so much harder, in my opinion, than the Champions League.
"Not the games but the recovery to play Premier League on the weekend, so we have to deal with that."