Barcelona have regained top spot in La Liga and piled more pressure on the shoulders of beleaguered Real Madrid manager Julen Lopetegui courtesy of a 5-1 win in the first Clasico of the season this afternoon.

Luis Suarez stole the show in the absence of the injured Lionel Messi with a hat-trick at Camp Nou, while Philippe Coutinho and Arturo Vidal bookended the rout with goals of their own.

Marcelo pulled one back to make it 2-1 early in the second half, and at one stage it looked as though they might fight their way back into the match, but three goals in the final 15 minutes saw Barca embarrass their bitter rivals to leapfrog Atletico Madrid in the table.

The result will force serious questions to be asked of Lopetegui, whose job was already understood to be hanging by a thread before the match with his side now ninth in La Liga and already seven points adrift of Barca having lost five and won just one of their last seven games across all competitions.

Barca quickly took control of possession in what was the first Clasico without either Messi or Cristiano Ronaldo on the pitch since December 2007, with Messi sidelined due to a broken arm and Ronaldo having left for Juventus during the summer.

Madrid have struggled since the latter's departure, and the early signs gave a hint that those troubles would continue at the home of their fiercest rivals as Barcelona quickly took control of the possession.

The first chance of the contest did fall the way of Madrid when Karim Benzema lashed a half-volley over the crossbar after being found by Gareth Bale, but Barca broke the deadlock just three minutes later.

A long spell of passes ended with Jordi Alba being released down the left flank, and the full-back had the time and space to pick out a low pass back to Coutinho, who swept a simple left-footed finish into the bottom corner.

Some poor defending almost gifted the home side a second after 19 minutes when Sergio Ramos put Nacho in trouble and the ball ended up at the feet of Arthur, who drew a one-handed stop from Thibaut Courtois from just outside the area.

Madrid did begin to grow into the match as the first half wore on, but they were limited to long-range efforts as Marc-Andre ter Stegen made routine saves to deny Bale, Marcelo and Ramos.

Barca doubled their advantage just as the visitors were enjoying their best spell of the half, though, with VAR being used for the first time in the Clasico to award the home side a penalty after Raphael Varane had clumsily brought down Suarez.

The Uruguayan stepped up himself and tucked a pinpoint spot kick into the bottom corner past Courtois, who guessed the right way but could not get a hand to the penalty.

Barcelona dominated the remainder of the half and it looked like it could get embarrassing for Madrid at one stage, with Rafinha curling one sight of goal high and wide from 20 yards.

Lopetegui's future looked fraught with danger at that stage, and eyebrows were raised when he chose to bring Lucas Vazquez on in the troublesome right-back spot during the interval, with Varane making way.

It was a change which initially looked to pay dividends as Madrid were almost unrecognisable in the opening stages of the second half, and their improvement led to them pulling a goal back as Barca's wait for a La Liga clean sheet extended to eight matches.

Isco's cross was deflected by Clement Lenglet into the path of Marcelo, who kept his composure inside the box to take touch and fire past Ter Stegen. The goal saw Marcelo score in three successive matches for the first time in his career, while he has now scored three of Real Madrid's four goals from their past seven outings.

Suddenly it was all Madrid as the players seemingly fought to save Lopetegui's job, and they were inches away from restoring parity when the ball broke kindly for Luka Modric, who saw his finish hit the inside of the post with Ter Stegen beaten.

Barca's defensive lapses - from which they have suffered all season - meant that a match they were controlling had turned into one on a knife edge, although they were also denied by the woodwork when trying to restore their two-goal advantage as Suarez's inventive volley from Sergi Roberto's cross came back off the post.

Alba then saw an effort of his own deflected narrowly wide after being picked out by Coutinho, but Madrid were still very much in the game and things may have been different had Benzema done better with a golden chance 22 minutes from time when he nodded over from a Vazquez cross.

It proved to be a pivotal moment in the match as Barcelona killed the game off and then rubbed salt into the wound during the final 15 minutes, with Suarez first restoring their two-goal lead with a brilliant header past Courtois from Roberto's cross.

Suarez's attempts to return the favour five minutes later proved unsuccessful when Roberto's header lacked the power to trouble Courtois, but the Uruguayan was back on the scoresheet again seven minutes from time to complete his hat-trick.

A mistake from Madrid captain Ramos gifted possession to Roberto, who immediately played Suarez through on goal and the striker - who has scored more Clasico goals than any other player since his arrival at Barcelona in 2014 - lifted a classy finish over the keeper to secure the matchball.

In the space of just 15 minutes Lopetegui had seen his side sink from the verge of a potentially job-saving comeback to a humiliating defeat at the home of their greatest rivals, and worse was to come with three minutes remaining when an unmarked Vidal nodded past Courtois moments after coming on as a sub.

The Madrid keeper did prevent things getting even worse in his first Clasico when he denied another acrobatic Suarez volley late on, and there was a chance for Madrid to make the scoreline look a little more respectable in stoppage time when Benzema was played through in the area, only to once again miss the target with his finish.

There was to be no softening of the blow for Madrid, though, as their worst start to a season since 2001-02 plunged to new depths to leave Lopetegui on the brink of seeing his reign end just 10 matches in to the La Liga campaign.

Los Blancos have now gone five league games without a win and lost three on the bounce for the first time since May 2009, while they have won just one of their last nine away outings across all competitions to leave themselves ninth in the table after 10 games.

Barca, by contrast, regain top spot and extend their unbeaten home league record to 42 matches, having also equalled the Clasico record by scoring in 22 consecutive matches against Madrid.

BARCELONA (4-3-3): Ter Stegen, Roberto, Pique, Lenglet, Alba; Rakitic, Busquets, Arthur (Vidal 84'); Rafinha (Semedo 69'), Suarez, Coutinho (Dembele 74')

REAL MADRID (4-3-3): Courtois; Nacho, Ramos, Varane (Vazquez 46'), Marcelo (Diaz 82'); Modric, Casemiro, Kroos; Bale (Asensio 77'), Benzema, Isco