Watch: Lionel Messi hat-trick sends Barcelona back to the top of LaLiga

Messi set Barca on their way with a penalty, but Lucas Olaza equalised with a fine free-kick for Celta's first goal under new boss Oscar Garcia.

The Barcelona number 10, though, soon had his side back in front just before half-time when he crashed home another superb deadball strike.

Messi completed his treble early in the second half, clipping the ball up and over the wall from 25 yards, and Sergio Busquets crashed in a late fourth.

Barcelona are level on 25 points with rivals Real Madrid, top on goal difference, while Real Sociedad are now two points behind following their draw against Leganes on Friday.

Earlier, Real Madrid hammered Eibar 4-0 to keep the pressure on at the top of the table.

Los Blancos hit three goals inside the first 30 minutes.

Karim Benzema broke the deadlock with an angled finish before captain Sergio Ramos added a second from the spot, and the French forward also converted a penalty.

Federico Valverde clipped in a fourth on the hour, his first LaLiga goal for Real Madrid, to seal a comfortable win for Zinedine Zidane's side, who followed up their midweek 6-0 Champions League thrashing of Galatasaray.

A strong second-half display gave Valencia a 2-0 win over Granada.

Daniel Wass opened the scoring with 16 minutes remaining and Ferran Torres added a second deep into stoppage time.

Alaves moved clear of the bottom three by thrashing Valladolid 3-0.

Joselu, Tomas Pina and Lucas Perez scored the goals as Babazorros El Glorioso climbed to 14th.