Real Madrid has been allowed to keep a commanding lead at the top of La Liga, despite a dip in form that has set nerves jangling about another second half of the season slide under Carlo Ancelotti.

Ancelotti's first spell in charge of Madrid was brought to an end in 2015 after a campaign in which Madrid won 22 consecutive matches before Christmas only to fall away from January, five defeats seeing it pipped to the title by Barcelona.

But Madrid appears unlikely to face such stiff opposition this term, with Barca and Atletico Madrid both scrapping to finish in the top four and its chief challenger, Sevilla, now stalling itself.

Madrid, which plays away at Rayo Vallecano on Saturday, strung together 13 wins in a 15-match unbeaten run through October to December but has been treading water since the turn of the year, with only three wins in their last six league games.

A shock defeat away at Getafe was followed by draws against Elche and Villarreal while a narrow victory over Granada, decided by a long-range shot from Marco Asensio, intensified concerns about a congealing attack.

Karim Benzema's absence was a huge blow, with the Frenchman missing three games with a hamstring injury before being rushed back to play in the first leg loss to Paris Saint-Germain in the Champions League last week.

And after a scintillating few months, Vinicius Jr. has plateaued too. The Brazilian has 16 goals for the season but has managed only one in the last six weeks, which came in the 3-0 win over Alaves on Saturday.

That result flattered Madrid, which was whistled at halftime by its own fans at the Santiago Bernabeu and might have been made to feel even more uncomfortable had the tension not been broken by another wonder-strike from Asensio.

Vinicius and Benzema added some shine with goals in the 80th and 90th minutes.

"What the fans thought, we agreed," Ancelotti said after that game. "Nobody in the dressing room was happy with that first half."

Many suspect fatigue is a factor in Madrid's downturn, accusing Ancelotti of failing to rotate his squad and relying too heavily on the same starting lineup, which includes veterans like Benzema, Luka Modric, Toni Kroos and Casemiro.

After an exhausting outing in Paris last week, when Madrid spent most of the night without the ball, Ancelotti made only one change against Alaves, as Fede Valverde came in for Kroos in midfield. Casemiro, who looked like he needed a rest, was particularly out of sorts.

Yet 14 points earned out of a possible 24 in La Liga has still been enough to furnish a six-point lead, which was extended last weekend after Sevilla was held by Espanyol.

That draw at Cornella was Sevilla's fourth in its last five matches, all of them coming against teams lying outside the league's top eight.

Sevilla is well-organized and defensively solid but coach Julen Lopetegui has been criticized for exercising too much caution against lesser opponents.

The team also suffered from numerous injuries while Anthony Martial, on loan from Manchester United, is yet to catch fire.

The result is a complete absence of pressure on Real Madrid, which still has to visit both Sevilla and Atletico Madrid during the run-in but might have a hefty enough cushion for those games not to be decisive.

Sevilla faces Real Betis on Sunday, with Betis, in third, able to move to within two points of its city rival with a victory in the derby the Ramon Sanchez Pizjuan.

Atletico will also be under pressure when it plays at home to Celta Vigo on Saturday, hoping to sustain some momentum on the back of their encouraging display against Manchester United in midweek.

Barcelona, which is level with Atletico on points but has a game in hand, hosts Athletic Club while Villarreal, which is three points behind in sixth, faces Espanyol earlier on Sunday.