Van Nistelrooy's late double keeps Real on track
A staggering 36 points separated Real and Levante before kick-off but on the pitch there was little to choose between them before Dutch striker van Nistelrooy's stole the points with his 10th and 11th goals of the campaign.
The Dutch forward put Real ahead on 76 minutes from the penalty spot before adding a second two minutes from time with a clinical right-footed strike.
Real now lead Barca, who beat Murcia 4-0 on Saturday, by seven points with Espanyol in third despite seeing their 14-match unbeaten run come to an abrupt end with a surprise 1-0 loss at Almeria on Sunday.
Espanyol had not lost since a 2-1 defeat to Recreativo Huelva at the end of September but an 87th minute goal from Kalu Uche ended that sequence.
"It was our worst away performance of the season," admitted Espanyol boss Ernesto Valverde.
Villarreal are now breathing down their necks after a 4-3 comeback win over strugglers Deportivo La Coruna.
Turkish international Nihat scored twice in as many minutes to help Villarreal move back into the top four and close to within a point of Espanyol. Villarreal looked to be heading for their seventh defeat of the campaign trailing 2-1 but Nihat struck twice, in the 66th and 68th minutes, to turn the game in their favour and propel them into the Champions League spots.
"We were poor for 65 minutes and good for 25," confessed Villarreal coach Manuel Pellegrini.
"Conceding so many goals makes it difficult to have a good campaign but reaching 35 points at this stage means there are more positives than negatives."
Fernando Gago started in the midfield for Real with Mohamadou Diarra gone for the African Nations Cup and Miguel Torres replaced the suspended Sergio Ramos at right back.
Goalkeeper Iker Casillas shrugged off a bout of gastro-enteritis to start with manager Bernd Schuster seemingly reluctant to field former Liverpool goalkeeper Jerzy Dudek.
Levante started the better with Real squandering possession far too easily but the champions look so dangerous going forward and Julio Baptista and Raul both had efforts cleared off the goal-line.
In the second half Baptista and Brazilian compatriot Robinho both hit the post as Levante rode their luck.
Real had only failed to score in of the their previous 18 league matches and the breakthrough came on 76 minutes with Jose Serrano unfortunately handling in the penalty area.
Van Nistelrooy made no mistake with the penalty sending the goalkeeper the wrong way and he scored again on 88 minutes as Real took the spoils.
At the opposite end of the table Real Betis climbed out of the bottom three with a crucial 3-2 home victory over fellow strugglers Getafe.
A brace from Argentine Hugo Pavone and an Edu strike clinched a fourth win of the season for the Seville club who moved up to 16th.