The Chelsea Women's team began the night top of their group, but ended being knocked out following a shocking 4-0 defeat to Wolfsburg.
Going into the game the Blues looked sure to go into the next round of the European competition given they had won four of their last five games in the Women's Super League.
However, the Chelsea Women's boss has said that her players were not themselves and 'heads were all over the place' regarding the ongoing rise of Covid infections.
Speaking on Thursday evening following the heavy defeat, Hayes said: "A few days ago we had two players struck down with Covid, and we know inevitably when we land home tomorrow there will be positive cases.
"Our heads were all over the place. We are human beings. The stress, the anxiety, the worry of having to perform in a game when you're thinking 'I just want to go home, I haven't seen my family, I've been to an Olympics - oh no another Christmas alone'.
"I'm not making excuses for the players, but I can tell you the last three days have been all over the place with the worry that we have to play this game.
"So while fixture congestion is a thing, Covid is real, and when you're in a team environment you know that is spreads like wildfire."
The number of postponements to fixtures across both the women and men's leagues have shot up this week, with ties called off on the day of matches due the sharp rise of cases of COVID-19.
As football heads into the match-packed Christmas period as infections sore, Hayes is not the only football manager fearing the impact of the current Covid situation on their team's performances, and inevitably, their seasons.