Jeremy Mathieu headed home a vital winner 16 minutes from time as Barcelona ground out a 1-0 win at Celta Vigo to remain four points clear of Real Madrid in La Liga on Sunday.

Earlier, Cristiano Ronaldo's first ever five goal haul had taken Madrid back to winning ways in stunning style with a 9-1 thrashing of Granada.

Mathieu had opened the scoring in Barca's 2-1 victory over Madrid last time out and just his second league goal for Barca could be just as crucial as they laboured for long spells against a well-organised Celta side.

There were no such troubles for Madrid, as after Gareth Bale's opener, Ronaldo took over as he scored three times in eight minutes just after the half hour mark.

Karim Benzema struck twice either side of Ronaldo's fourth as Real added three more in a four-minute spell just after the break.

Robert Ibanez grabbed a consolation for the visitors, but Diego Mainz's own goal made it 8-1 before Ronaldo rounded off the scoring with a towering header.

Meanwhile, Valencia's outside hopes of a late title challenge were dented as they remain in fourth, nine points off the top, after a 0-0 draw at home to Villarreal.

Celta stunned Barca at the Camp Nou when they last met back in November and the visitors knew they were in for another uncomfortable 90 minutes when Claudio Bravo had to turn away former Barca forward Nolito's low drive 10 minutes in.

At the other end Messi was first to threaten as Sergio Alvarez did well to parry his curling effort before Neymar fired the rebound well over.

The best chance by of the opening 45 minutes fell to Celta's Joaquin Larrivey, but the man who scored the winner at the Camp Nou blazed over with just Bravo to beat.

Barca started the second period brightly and could have been in front as Neymar had a sweetly struck goal ruled out for a marginal offside call.

In the end the visitors had to rely on a set-piece to get the job done as a wonderful in-swinging free-kick from Xavi was met by a equally good header by Mathieu to thunder the ball in off the crossbar.

Celta then ended the game with 10 men as Fabian Orellana was sent off in bizarre circumstances for throwing a clump of turf at Sergio Busquets.

However, a lean night in front of goal for Lionel Messi means Ronaldo's quintuple takes him four clear of the Argentine in the race to be La Liga's top goalscorer.

"Happy to have scored five goals with this excellent team work. Thank you for all your support," Ronaldo posted on his official Twitter account.

"What more can I say about him? It is the first time he has scored five goals with Real Madrid which is great for him and for us looking forward to the next game," said Madrid boss Carlo Ancelotti.

Bale was first to capitalise on some terrible Granada defending when he latched onto Toni Kroos's through ball to round Oier Olazabal and slot home from a narrow angle.

James Rodriguez made his return after two months out with a foot injury and sealed his comeback with a lovely assist with the outside of his left foot to allow Ronaldo to curl home his first of the afternoon.

The Portuguese soon made it 3-0 by lashing home from close range after Olazabal had spilled a cross and he sealed an eight-minute hat-trick with some more help from the Granada 'keeper as he couldn't keep out the World Player of the Year's drive from 20 yards.

Granada offered embarrassingly little resistance after the break as Benzema was given plenty of time to control a corner from the left and fire home to make it 5-0.

Bale then unselfishly teed up Ronaldo to nod home his 46th goal of the season, although there was a brief scare for the home fans as Ronaldo collided with the frame of the goal in doing so but was soon back on his feet.

More shocking defending from Granada allowed Benzema to saunter through for a seventh barely 60 seconds later.

Granada pulled a goal back when Ibanez burst clear of Raphael Varane to slot past Casillas, but their miserable day was rounded off when Mainz could only turn Luka Modric's cross into his own net.

And fittingly Ronaldo had the final word when he rose highest to power Modric's free-kick in at the far post.