Two goals from the Argentine in the first period surpassed Gerd Muller's record of 85 goals in a calendar year, but the party was spoiled on the stroke of the interval as Ruben Castro cut the score to 2-1 at the interval.
Betis hit the woodwork three times in the second period, but they could not force it over the line as Barcelona held on for yet another three points in a quite remarkable start to the season.
Read how it all unfolded in Sports Mole's minute-by-minute live commentary of the action.
Real Betis: Adri; Chica, Amaya, Dorado, Nacho; Benat, Sevilla, Carlos, Canas; Campbell, Castro
Barcelona: Valdes; Adriano, Pique, Puyol, Alba; Xavi, Fabregas, Busquets; Iniesta, Messi, Pedro