Atletico Madrid boss Diego Simeone was left to rue his side's slow start after they were beaten 2-1 at Rayo Vallecano on Sunday.
Rayo roared out of the blocks with goals from youngsters Lass Bangoura, 20, and Leo Baptistao, also 20, as the club with the lowest budget in the division moved up to sixth place.
Simeone told reporters at Estadio Vallecas that the better team had won, saying: "Rayo started well, and we need to give them credit.
"There is no need to go looking for criticism when the team loses. Rayo started better than us, scored quickly, and had the wind in their sails. Rayo were better, and that is football."
Atletico have lost four of their last five away games and lie 12 points behind leaders Barcelona but are still four ahead of city rivals Real Madrid.
Simeone said his team had improved after the break but were unable to find a way back into the game, with Radamel Falcao's goal coming in the fifth minute of stoppage time.
"In the first half we did not play well, but in the second we were better," he said. "We had some chances, above all from Filipe Luis. In the first half Rayo were superior - in the second they almost never came near our goal."
Rayo coach Paco Jemez said his attacker Leo, who is reportedly interesting Manchester United but has reportedly agreed to join Atletico next season, was unlikely to stay at Vallecas beyond the summer.
"It is difficult for him to play badly," Jemez said. "We hope to be able to enjoy his talent and his commitment for the next four months."