The Belgian atoned for his own error late on to ensure that his side remains atop La Liga, but the club failed to take advantage of Barcelona's slip-up at Elche.
Atletico Madrid remains in pole position to claim the Liga title after Toby Alderweireld's late header saw it come from behind to draw with Malaga.
Diego Simeone's side went into the clash three points clear of Barcelona, which could only manage a draw with Elche.
That leaves Atleti needing just a draw from its clash at Camp Nou next week to win the title.
David Villa – replacing the injured Diego Costa (thigh) – came closest to scoring in the first half, hitting the bar when one-on-one with Malaga goalkeeper Willy Caballero.
Atletico dominated the first hour but was made to pay for its profligacy when Samuel Garcia gave Malaga a shock lead in the 65th minute.
Alderweireld failed to deal with a long ball which allowed Samu to get in behind the defense and lob the onrushing Thibaut Courtois before heading in from an angle.
The defender then went from zero to hero when he headed in a 74th-minute corner before Malaga went down to 10 men after defender Marcos Angeleri was sent off in the dying stages. Adrian Lopez was sensationally denied by Caballero in stoppage time.
The draw secures Malaga's top-flight status, while Atletico will go into its title showdown with defending champions Barca hoping it does not rue two dropped points.
Costa was not Atletico's only absentee, with suspended defender Diego Godin replaced by Alderweireld, but the Belgium international had little to do in the first half as the hosts dominated without scoring.
Diego Simeone's side first went close in the fifth minute when Tiago's stabbed effort went out for a corner via the arm of Eliseu.
Atletico's penalty appeals were waved away and in truth Malaga would have been unlucky if referee Jose Teixeira pointed to the spot, given the close proximity of the defender to Tiago.
Villa's chance followed, but he could only hit the crossbar after being sent through by Raul Garcia's flick-on header.
And the hosts headed to the break frustrated after they failed to convert two excellent Juanfran crosses.
The initial chance was poked wide by Koke, who preferred to use his right foot when it seemed easier to shoot on his left, before Garcia nodded a free header wide, although he was distracted by Alderweireld going for the same ball.
Atletico's pressure kept coming after the break as Koke dragged an effort wide before Villa was kept out by Caballero from a tight angle.
With the hosts pouring numbers forward they were vulnerable to counter attacks, and Simeone had Courtois to thank for his excellent save to deny Roque Santa Cruz on the hour mark.
The one-on-one chance served as a warning for Atletico and it was one it did not heed as Samu kept his composure to nod in the opener after lifting over Courtois.
Diego had a shot pushed wide with 18 minutes left and less than 60 seconds later Villa was denied by Caballero after a well-worked set piece.
Atletico's pressure eventually told, though, as Alderweireld made amends by rising highest to head a corner past Caballero and in.
The hosts could not find a winner despite Angeleri's second yellow card with three minutes left, meaning the stakes could not be higher for their trip to Barcelona.