Pires out to stop Barca clean sweep
Pep Guardiola's side have swept all before them winning 12 of their last 13 matches to go eight points clear at the top of the standings, and fourth-placed Villarreal have the last chance to trip them up before the winter break.
Barca's run has seen them demolish second-placed Valencia 4-0, third-placed Sevilla 3-0, and fifth-placed Atletico Madrid 6-1. Last weekend, champions Real Madrid succumbed 2-0 to slip down to sixth.
"Barca are the best team in the league by a long way but they are not invincible," Villarreal's French midfielder said.
"We have done well against Barca in recent meetings and beaten them a few times. It suits us that they play a similar style of football."
Villarreal have beaten Barca the last three times they have met in the league but their form has dipped of late and they have only won one of their last five league outings. They will be without suspended top scorer Joseba Llorente.
The weekend's other outstanding encounter sees struggling Real Madrid host Valencia on Saturday.
For Valencia it is a chance to avenge their defeat in the season-opening Spanish Super Cup, when they let slip a 3-2 first leg advantage to lose 4-2 at the Bernabeu against nine men.
"As a footballer you feel the need for revenge because of the way we lost that game (the second leg)," Valencia winger Joaquin said earlier in the week.
"It's clear Real Madrid are not in good shape but we cannot fall into the trap of thinking it will be easy to beat them."
Real's new coach Juande Ramos lost his first league game in charge at the Nou Camp last weekend, but was pleased with the spirited way in which they thwarted Barca for long periods.
However, the Bernabeu will demand a more attacking approach at home which will be a risky proposition against their quick-breaking visitors.
Real have lost four of their last five league matches and are weakened by injuries, added to which defender Sergio Ramos is suspended. Winger Arjen Robben returns after missing the Barca game.
In-form Atletico Madrid will be looking to build on their 14 match unbeaten run in all competitions when they visit Espanyol on Saturday and Sevilla visit troubled Real Mallorca on Sunday.