Midfielder Casemiro conceded Real Madrid are experiencing a "difficult moment" and must work harder after they suffered a stunning 2-1 defeat to Girona on Sunday.
Goals from Cristhian Stuani and Portu in four second-half minutes overturned Isco's opener as the hosts claimed a famous victory.
Madrid's defeat means Zinedine Zidane's side are now eight points off LaLiga leaders Barcelona after just 10 matches.
"We're worried about everything now," said Casemiro.
"We know we're very far behind. We must keep our heads now, this is a difficult moment. We did not play well today. We must play better, we must work harder.
"Girona played well in the second half - we must congratulate them."
1990- Real Madrid have lost vs a newly promoted in their 1st ever meeting in La Liga for the 1st time since 1990 (vs Real Burgos). Stumbling pic.twitter.com/QTbiSmHxOr-- OptaJose (@OptaJose) October 29, 2017