JOIN USChampions Barca, two points clear of Real with 43 from 17 games, had goalkeeper Victor Valdes to thank for setting up their first win of 2010.
Valdes saved three one-on-ones in the early stages –– the first deflected on to the crossbar –– before Barca found any kind of rhythm in the face of frenetic pressuring from their hosts.
Bojan Krkic, in for the suspended Zlatan Ibrahimovic, set up Messi for the opener in the 36th minute and Carles Puyol headed the second from a Messi free kick in the 44th.
Messi poked in the third after excellent approach play from Andres Iniesta and Krkic. The Argentine lobbed the fourth, his 12th of the campaign, from outside the area in the 75th before defender Ezequiel Luna scored an own goal to complete the rout.
Real were quickly in front at a snowy Bernabeu when Gonzalo Higuain cut in from the right flank and curled a shot into the top corner after seven minutes.
With Kaka back in the side after over a month on the sidelines with injury, Real were sharper in every department against a team that had started the weekend in fourth.
Cristiano Ronaldo and Kaka went close but the second goal did not arrive until the 49th when Higuain's cross was volleyed in by Esteban Granero.