Defeat on Saturday would have made Barcelona champions before they kicked a ball this weekend, but a second-half own goal from Joaquin Fernandez gave Atletico a win that means the leaders must beat Levante later in order to guarantee the title.
The goal was an unfortunate moment in an otherwise strong performance from the visitors, who could find themselves back in the relegation zone if other results now go against them.
There were more bookings (four) than shots on target (three) in a poor first half, with Jan Oblak making one good save to deny Sergi Guardiola from 20 yards out.
Antoine Griezmann could not quite steer a shot into the right-hand corner after good play from Alvaro Morata, but Atleti were struggling to control the pace of the game without Rodrigo in central midfield, and he was introduced at half-time for the ineffective Thomas Partey.
Atleti's increasing pressure was still yielding few chances until 65 minutes in, when Saul Niguez's good run and cross from the left saw Joaquin head the ball into his own net.
Oblak superbly kept out a fierce Oscar Plano strike as Valladolid pushed for a leveller, and there was a moment of controversy two minutes before the end of normal time when referee Mario Melero Lopez opted not to award the visitors a penalty for handball despite checking the VAR monitor.
Miguel de la Fuente was denied by another strong Oblak save in injury time, as Atletico just about managed to keep the pressure on the leaders.
Title race is just about alive
As it stands now, Ernesto Valverde's Barca will need to beat Levante later on Saturday if they are to secure the title this weekend, meaning Atleti are still just about in the race.
It could be a costly defeat for Valladolid, though, who will drop into the bottom three if Girona beat Sevilla on Sunday.
