Valencia bolstered their bid to secure Champions League football next season with a 2-1 victory as Jonas nodded in a last-gasp winner to break the hearts of 10-man Real Valladolid.
Los Che looked to have blown their chance to claim all the points after failing to build on the lead gifted to them by Mikel Balenziaga's first-half own-goal.
Henrique Sereno was handed a second yellow card for the foul that saw Valencia awarded a penalty in the 57th minute, but Roberto Soldado was unable to capitalise as his spot-kick was saved by the impressive Dani Hernandez.
The 10 men of Valladolid looked to have secured an unlikely point after Oscar Gonzalez lashed home a fine effort in the 71st minute, but with just 10 seconds left in added time Jonas rose to nod in Jonathan Viera's pinpoint cross.
The victory sees Valencia stay within two points of Real Sociedad in the race for the fourth and final Champions League berth.
Valencia boss Ernesto Valverde called on his players to ignore the boardroom unrest at the club heading into the match after president Manuel Llorente resigned on Friday.
Llorente quit reportedly in protest at boardroom changes, while vice-president Jose Antonio Garcia Moreno also left his post.
The off-field issues could easily have prove a distraction to Los Che, but they looked focused on the job at hand.
They carved out the first chance in the 23rd minute when Sergio Canales latched onto a defence-splitting pass only to misjudge his attempted chip, with Dani patting the ball down before bravely diving at the feet of Soldado to smuggle away the rebound.
The breakthrough arrived in fortunate circumstances in the 39th minute when Tino Costa's corner cleared several heads in the six-yard box and went all the way through to Balenziaga, who hung out a leg to deflect the ball into his own net.
Valladolid were denied an equaliser three minutes into the second half only thanks to the brilliance of Vicente Guaita, who went full-stretch to his right to spectacularly turn away Omar's powerfully-struck effort.
The visitors' hopes were hit in the 57th minute when Tino Costa robbed Jesus Rueda in midfield and played in Soldado, who was crudely hauled down in the area by Sereno.
The Valladolid defender received a second yellow card for his trouble, but when Soldado stepped up to take the penalty Dani guessed right to make the save.
Moments later Jonas turned smartly in the box before firing in a low shot that Dani again was equal to, while at the other end Manucho almost pulled a goal out of nothing when he hit an optimistic effort from 40 yards that had Guaita scrambling.
The warning signs were there for Valencia and on 71 minutes Valladolid pulled level with a goal of real quality, Antonio Rukavina making progress down the right and crossing for Oscar - who lashed home first time into the top-right corner.
The points looked destined to be shared as Valencia struggled to mount meaningful attacks in what time remained, but all that changed with seconds remaining as Viera was given the freedom of the Mestalla to pick his cross from the right and Jonas did the rest with a fine angled header.