Carlo Ancelotti admitted that Real Madrid's 2-1 defeat at Real Betis on Saturday could prove "costly" in the LaLiga title race.
Brahim DÃaz put Madrid ahead early on at the Benito VillamarÃn, but Betis and U.S. men's national team midfielder Johnny Cardoso levelled with a header before half-time.
Former Madrid player Isco put Betis ahead with a second-half penalty, to see the reigning champions drop three valuable points in their battle for the title with Atlético Madrid and Barcelona.
"It was a bad game," Ancelotti said in his post-match news conference. "We started well, but then we couldn't maintain our rhythm. We lost control of the game, against a team that played better than us and deserved to win.
"This is a real blow. We have to react. Losing at this stage of the season is costly. We didn't do well ... We lost the ball 27 times in the first half. That's too many."
Madrid are chasing three major trophies, having beaten Real Sociedad 1-0 in their Copa del Rey semifinal on Wednesday, and now preparing for a Champions League round-of-16 first leg clash with Atlético on Tuesday.
"If we play like this, we won't win on Tuesday, that's quite clear," Ancelotti said. "I hope this will wake us up. It seemed like lately we had been more organized, and more compact. And today we weren't able to do that."
Ancelotti opted to substitute star forward Kylian Mbappé in the 75th minute as Madrid chased an equaliser, replacing him with youngster Endrick.
"[Mbappé] had a problem this week [with his tooth] and he hasn't trained much," Ancelotti said. "He wasn't at his best, that was obvious. To avoid problems, I took him off and brought on Endrick."
Cardoso's goal was his first in LaLiga this season, having made 19 league appearances for Betis this campaign.
