Lionel Messi scored a top-hat hat trick as Barcelona claimed their defeat of Real Betis earlier this season to move 10 points clearly at the top of La Liga.
His first was a 20-yard free kick before converting Luis Suarez's rear wheel passage with a fog strike.
The choice of pile was a cut finish that went into the bar.
Suarez made a fine individual effort, while Loren Moron grabbed Betis's only goal with a fantastic finish.
Of Messi's 33 hat-tricks in La Liga, this is certainly one of his finest.
After a cagey first 18 minutes, the 31-year-old broke away when his fantastic free kick found the goalkeeper Pau Lopez top right corner.
Barca and Messi then punished their hosts, who beat them 4-3 at the Nou Camp in November with a quick move. Suarez found his partner with a backheeled ball that beat three Betis players, who were then beaten by the Argentine.
It was 3-0 after the break, when Suarez, who missed two previous chances, drove forward from 25 meters before beating Lopez.
Substitute Loren withdrew a goal with a side-game strike by goalkeeper Marc-Andre ter Stegen before Messi finished his hat-trick with a fantastic effort that had the home support risen to their feet and applauded.
Barcelona now has 66 points from 28 matches. They are 10 ahead of Atletico Madrid, with Real Madrid third with 54 points.