Valencia boss Gary Neville believes his side suffered from their exertions in holding Barcelona at the weekend as they crashed out of the Champions League with a 2-0 home defeat to Lyon on Wednesday.
The Spanish side needed to win and hope Gent dropped points at home to Zenit St Petersburg to qualify for the last 16, but they were stunned by an already eliminated Lyon side, who picked up their first European win of the season thanks to goals either side of half-time by Maxwel Cornet and Alexandre Lacazette.
Neville watched on the from the stands as a depleted Valencia battled back to seal a point against the European champions on Saturday thanks to Santi Mina's late equaliser.
However, they didn't reach the same heights in Neville's debut as a head coach as Lyon's pace tore the hosts apart on the counter-attack.
"When you have 10 injuries and the same players play every three days, particularly these type of games -- Sevilla, Barca, tonight versus Lyon -- you get a deterioration of sharpness," he said.
"One or two percent goes each time. I know from my own playing career that to have the same level of energy every three days is difficult.
"The effort against Barca was immense, out of this world, but today that same level of sharpness was just missing. It's not a fitness problem but a concern. We need to get players back and more freshness into the squad.
"We must take the defeat on the chin and realise it is unacceptable to lose at Mestalla. It's not something we can take lightly."
- Controversy -
The outcome could have been very different had Shkodran Mustafi's early headed goal not been controversially ruled out, but Neville accepted his side had been second best rather than point the finger at Slovenian referee Matej Jug.
"I've not seen the Mustafi goal yet, but players thought it was not a foul," he added.
"I can sit here and say if that counts, of course it is a different game. We can sit back and then counter. They scored first, which was important, it allowed them to counter on us rather than vice-versa.
"From that point of view, I used to whinge a lot as a player, but I wont blame refs as a manager unless I feel I have to and tonight I don't have to as Lyon did well in the game, so I won't create headlines about the ref."
A third-place finish in Group H means Valencia drop into the Europa League, just as Manchester United did 24 hours earlier.
Neville won 20 trophies with United over a 19-year playing career, but insisted a reunion with the Red Devils was the furthest thing from his mind ahead of his first La Liga game in charge away to Eibar on Sunday.
"We will take the competition seriously number one. Who we draw, and whether we play Man Utd, is the last thing on my mind at moment.
"I'm thinking about recovering for Sunday's league game. At this moment I couldn't care whether we play Man Utd or someone else in the Europa League. I have to think of tomorrow, the next day, and preparing players for Sunday."