Kevin De Bruyne believes the mental and physical toll of chasing the quadruple could make the feat nearly impossible for Manchester City.
City moved a step closer to an unprecedented clean sweep of four trophies by reaching the FA Cup final with a narrow 1-0 victory over Brighton at Wembley on Saturday.
Yet manager Pep Guardiola described the quad challenge as almost impossible after the game and De Bruyne agrees that the congested fixture list presents a tough obstacle.
“The Champions League is the same. So, it is difficult.”
City are now staying in London ahead of their next testing task, Tuesday’s Champions League quarter-final first leg at Tottenham.
To underline his point, De Bruyne noted that Spurs – who City also face in the Premier League this month – have had a free weekend ahead of the clash.
“We know Tottenham played their last game on Wednesday so they will be more fresh than us. We have to prepare ourselves mentally and physically to be ready.”
The game will be Spurs’ second at their new stadium, the move to which has given the club a lift.
But De Bruyne said: “The stadium doesn’t matter. They are going to be excited because it is a Champions League quarter-final.
“Spurs are a very good team. Everybody knows how they play. They will not change. It is going to be exciting, it is going to be tough because we play them three times in 10 days.”
He said: “Probably they will (win their games). We just have to look at ourselves and try to win game by game. We will see in the end what happens.
“No matter who is champion or second, we’ve had a great season. What can you say if you get 92 or 95 points and in the end you are second? Normally that’s historic in the Premier League, to get these points. Imagine being second with it.”
De Bruyne provided the one genuine moment of quality in a drab game against Brighton, curling in a brilliant fourth-minute cross for Gabriel Jesus to head the only goal. The Seagulls applied pressure in the second half but City comfortably closed out the win.
“We know how Brighton play,” De Bruyne said. “They played well and it was difficult for us but, except for one corner, I don’t think they threatened too much.”