An uninspired Blancos side had two late goals to thank as it turned the game on its head to earn three points against the relegation-threatened Andalusians.
Real Madrid left it late as the club struggled towards a 2-1 away victory against Granada to remain on course to finish the Liga campaign on 100 points.
Franco Jara grabbed the opening goal of the game in the fifth minute as an under-strength and under-par Los Blancos struggled to create anything of note. However, Cristiano Ronaldo's late penalty brought Madrid back into the game before David Cortes' inexplicable own-goal during injury time earned the newly-crowned champion the win.
Granada lost its discipline at the full-time whistle as Moises Hurtado and Guilherme Siqueira picked up red cards with Resino's side's survival in the Spanish top flight still in doubt.
Madrid made a shaky start to proceedings and found itself a goal down in the fifth minute. Picking the ball up on the halfway line after dispossessing Marcelo, Jara stormed past Ricardo Carvalho into the box before coolly slipping the ball underneath Antonio Adan's legs to find the back of the net.
Resino's men were nearly in wonderland two minutes later as they came mightily close to adding a second. Odion Ighalo's shot from the edge of the area was parried away by Adan before the Nigerian's rebound effort was cleared off the line by Marcelo - the Brazilian appearing in the right place at the right time to save his team further embarrassment.
Despite fighting their way back into the game, Los Blancos struggled to create goalscoring opportunities and had to wait until the 36th minute to have a shot at goal. Nuri Sahin picked the ball up 25 meters from goal before unleashing a swerving drive which narrowly cleared the crossbar.
Mourinho's men saw their first clear-cut chance of the match appear in the 42nd minute and Cristiano Ronaldo was guilty of missing a glorious opportunity from close range. Karim Benzema held the ball up well before clipping a clever cross into the six-yard box, yet his Portuguese teammate could only screw his header wide of the target, much to the relief of Julio Cesar in the Granada goal as the home team headed into the interval 1-0 up.
The 2011-12 champion started the second period brightly after Gonzalo Higuain replaced Kaka and Xabi Alonso came in for Sahin, and the club came close to the equalizer on 58 minutes. Marcelo's cross-field ball evaded the Granada defense and found Benzema on the right side of the box. The Frenchman took one touch to bring the ball under his control before smashing it towards the top corner from a narrow angle - a shot which Cesar was equal to, parrying the ball out for a corner.
Seven minutes later Higuain slipped a clever through-ball into the path of Ronaldo but the former Manchester United man was faced with an angle too tight as his eventual effort was easily blocked by the goalkeeper.
Madrid was handed the opportunity back into the match in the 79th minute when Moises was penalized for wrestling Ronaldo to the floor in the box, earning himself a yellow card in the process. The Portuguese attacker stepped up to take the penalty himself, slamming his spot kick in the bottom corner sending the keeper the wrong way to bag his 45th league goal of the season.
The away team was to deal Granada a bitter blow when Benzema's cross into the box in injury time was turned into his own net by David Cortes to gift Mourinho's side all three points as Moises and Siqueira saw red cards after the final whistle.
Real finishes it championship-winning campaign at the Bernabeu next weekend against Mallorca, needing a win to set a new Liga record of 100 points in a single season, while Granada visits Madrid to face Rayo Vallecano in a direct scrap for survival.
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