(Photo credit: David Frerker-Imagn Images)

Fernando Tatis Jr. knocked in two runs Thursday and Walker Buehler pitched into the sixth inning for his first win with the San Diego Padres as they stretched their winning streak to eight games with a 5-2 verdict over the visiting Seattle Mariners.

Buehler (1-1) took a 4-0 lead into the sixth before Seattle reached him for three straight hits, the last an RBI single by Cal Raleigh. But he limited the Mariners to two runs on five hits with a walk and seven strikeouts.

Four relievers took care of things from there with closer Mason Miller logging his sixth save by striking out the side in the ninth. That enabled San Diego to sweep the three-game series and finish the homestand with a 7-0 record.

Luis Castillo (0-1) absorbed the loss after giving up seven hits and four runs (one earned) over 5 1/3 innings. He walked three and fanned three.

Castillo's trouble all came in the second, when he allowed four hits and did some damage to himself. His low throw to first on Jake Cronenworth's comebacker gave the Padres a fourth out, and as they've done during their winning streak, they capitalized.

Luis Campusano knocked in the first run with an RBI single and Ramon Laureano made it 2-0 with a groundout to first. Tatis followed by lacing a two-run single to left-center, giving San Diego all the offense it needed.

Seattle had its chance to change the game's arc in the sixth. After chasing Buehler, it got within 4-2 when Julio Rodriguez greeted reliever Bradgley Rodriguez with an RBI single. But Adrian Morejon rode in from the bullpen when the Mariners filled the bases with one out and quashed the threat with a strikeout of pinch hitter Connor Joe and a groundout.

The Padres tacked on an insurance run in the seventh when Manny Machado blooped a single over a drawn-in infield to score Tatis.

Machado and Miguel Andujar each collected two of San Diego's 10 hits.

--Field Level Media