Barcelona look to extend their four-point lead at the top of La Liga against an old friend turned foe in Celta Vigo coach Juan Carlos Unzue on Saturday.

Meanwhile, Real Madrid travel to a struggling Athletic Bilbao with their eyes firmly on one of Athletic's rising stars.

Here, AFP Sport looks at five things to look out for in La Liga this weekend.

Gareth Bale's emergence off the bench to save a faltering young Real side from embarrassment against third-tier Fuenlabrada in the Copa del Rey earned the Welshman rave reviews in the Spanish press on Wednesday.

Marca declared Bale had been handed a "fresh start" after a year dogged by a series of injuries.

Yet, he could be absent again at San Mames due to a niggling calf problem having missed training for the past two days.

Unlike Bale, Keylor Navas didn't help Madrid on his return to action after six weeks out by turning Fuenlabrada's opener into his own net in midweek.

Kiko Casilla was also at fault for Malaga's second goal at the Bernabeu last weekend, intensifying Real's search for a new goalkeeper.

According to reports, the new man will be Athletic's Kepa Arrizabalaga, who has been one of few shining lights in a hugely disappointing season for Bilbao.

Arrizabalaga didn't feature as the Basques did suffer Cup humiliation at the hands of tiny islanders Formentera on Wednesday, edging coach Jose Angel Ziganda closer to the sack.

Unzue returns to the Camp Nou hoping to continue Celta's record of beating Barca once in each of the three previous seasons when he was assistant to Luis Enrique.

Celta's daring approach against the Catalans in recent years has though had mixed success.

Whilst they have twice hit Barca for four at home, in their last two visits to the Catalan capital Celta have been smashed 6-1 and 5-0.

Las Palmas are looking for already their third coach of the season after Pako Ayestaran was sacked on Thursday.

Ayestaran was only appointed in September when Manuel Marquez resigned.

How the Islanders must wish they had held on to the man they will face this weekend back when Quique Setien brings Real Betis to the Canary Islands.

Setien not only kept Las Palmas up in the previous two seasons, but did so thanks to some thrilling attacking football.

That has continued at Betis, whose 13 La Liga games this season have produced 50 goals.

However, contractual differences with the board saw Setien walk out in the summer and left Las Palmas in the lurch.

Valencia kept their unlikely title challenge alive by holding Barca at home last weekend.

That point came at a cost, thought, as PSG loanee Goncalo Guedes suffered a broken toe that is expected to keep the Portuguese winger out for the rest of the year.

Guedes's three goals and five assists have played a huge part in Valencia's revival.

However, a kind fixture list during Guedes's absence offers Valencia hope with a visit to Getafe on Sunday followed by Celta, Eibar and Villarreal before the winter break.