SAN FRANCISCO -- A weekend series in San Francisco presented the Padres with a unique opportunity. There are six other teams currently in the National League playoff picture. This weekend, those six teams played each other.

Which gave the Padres this assurance: If they won, they knew they’d gain ground on ... somebody.

And they took full advantage. San Diego completed a sweep of the Giants with a 4-3 victory in 10 innings on Sunday afternoon at Oracle Park. Fernando Tatis Jr.’s eighth-inning homer -- the first of his career as a pinch-hitter -- put them on top. After Robert Suarez’s second blown save in three attempts, the Padres pulled ahead for good with a two-run rally in the 10th.

In the process, they moved within three games of the Dodgers in the National League West race, ahead of Los Angeles’ series finale against the Braves on Sunday Night Baseball.

In fact, the Padres emerged from their weekend series closer to the top of the division than the cut line. Their sweep moved them 3 1/2 games ahead of the Mets, currently the first team on the outside of the playoff picture.

The win also moved the Padres 20 games above .500 for the first time since 2010.

Left-hander Martín Pérez, who returned from the paternity list on Saturday, pitched five-plus innings of one-run ball, continuing his excellent run since joining the Padres at the Trade Deadline. He's posted a 2.72 ERA in eight starts with San Diego.