Fiorentina coach Vincenzo Montella says they suffered from fatigue for defeat at home to Cagliari.
This is the first time since February 2012 that the Viola have lost three Serie A games in a row.
"Today we suffered from a lack of nervous energy," the Coach told Sky Sport Italia.
"Thursday's Europa League quarter-final sapped our reserves and we cannot afford to play in a certain way at this level.
"The team did work hard, albeit in a confused manner, but couldn't keep the necessary concentration and determination.
"Now it becomes even more difficult to defend sixth place and qualify for Europe. A victory would've been so important, but we have to accept this loss and not lose confidence.
"We must relax and realise we can do so much better."