SAN FRANCISCO (AP) Buster Posey is hitting, moving on the bases and catching with an encouraging strength in mid-September for someone who had hip surgery three years ago and chose to sit out the shortened 2020 season to protect his young family.

And he is determined to keep playing deep into October.

Posey homered in the first inning and beat out an infield single then scored the go-ahead run on an error in the third, and the San Francisco Giants beat the San Diego Padres 6-1 on Tuesday night for their ninth straight victory a day after becoming the first team in the big leagues to clinch a playoff berth.

''I feel good, I feel like my legs are underneath me,'' Posey said. ''I've been trying to implement that at the plate.''

Brandon Belt and Darin Ruf each hit run-scoring doubles and Tommy La Stella added an RBI single to back Anthony DeSclafani (12-6), who won for the first time in five starts since defeating Colorado on Aug. 13. The right-hander had allowed six earned runs over his previous 14 2/3 innings.

Belt, who proclaimed himself captain last week in Chicago, formed a `C' with his hand after the eighth-inning double.

With nine straight wins, the majors-best Giants (95-50) have their longest winning streak since a 10-game unbeaten run from May 20-31, 2004.

Posey was part of the World Series championship teams of 2010, `12 and '14 - and these Giants are showing signs of delivering another special postseason.

''You appreciate it for sure,'' Posey said. ''But at the same time, all the guys have such a healthy urgency every day, so you can't sit back and reminisce at this point. There's still a lot of work and guys are getting to the ballpark each day and putting that work in and preparing and going out trusting that the work we've done leading to that is going to pay off.''

DeSclafani allowed one run on three hits, struck out three and walked one over 6 2/3 innings.

Jake Arrieta (5-13) lasted just 3 2/3 innings for San Diego in his third start since signing as a minor league free agent Aug. 16. Arrieta allowed three runs over five innings during his last outing against the Astros and has lost nine of his last 14 outings overall.

San Francisco's Kris Bryant hit his 200th double in the second - off his old Cubs teammate in Arrieta. The pitcher's wild throw to first on a pickoff attempt allowed Posey to score for a 2-1 lead in the third.

Posey's 18th homer of 2021 marked the 11th longball in as many games surrendered by San Diego - which has allowed opponents to clear the fences 18 times since Sept. 1.

Trent Grisham hit an RBI groundout in the third for the Padres, who dropped a fifth straight - but they're still in the wild-card race, and ''that's the encouraging thing,'' manager Jayce Tingler said. ''... It's still right in front of us with 18 to go.''

''I think there's a little bit of pressing,'' right fielder Wil Myers said.

Tingler credited DeSclafani but knows his offense needs to snap out of it.

''It's more on us scuffling, struggling, not having the at-bats that we're capable of in a slump,'' Tingler said.

WHAT A RUN

The Giants have scored at least six runs in nine straight games - most in the club's San Francisco history dating to 1958 and trailing only a stretch of 15 such games accomplished in 1929, which marks the longest run in baseball history since at least 1909.

''I think we've had a consistent approach recently,'' manager Gabe Kapler said. ''We've stayed with the concept of looking for specific pitches and pitches and we can drive and do damage on and being patient on pitches that we can.''

TRAINER'S ROOM

Padres: 1B Jake Cronenworth (fracture in left ring finger) hit against front toss Monday and began taking some batting practice swings Tuesday, perhaps signaling a potential return this weekned. ... LHP Blake Snell, the 2018 AL Cy Young Award winner who exited in the first inning of his Sunday start against the Dodgers with a left adductor strain, is still undergoing treatment.

Giants: LHP Alex Wood, working back from a bout with COVID-19, might be ready to throw live batting practice Wednesday. ''We'll see how he comes out of this,'' Kapler said. ''If he's feeling good we can decide what the next steps are. He's moving in the right direction.'' ... OF Alex Dickerson (right hamstring strain) and INF Donovan Solano (COVID-19 injured list) both were continuing their rehab assignments with Triple-A Sacramento.

ROSTER MOVE

The Padres signed LHP Ross Detwiler to a major league contract and optioned RHP Shaun Anderson to Triple-A El Paso.

UP NEXT

RHP Joe Musgrove (10-9, 2.93 ERA) starts for San Diego seeking his third win in four starts but coming off a loss to the Dodgers his last time out.

The Giants' starter for Wednesday night's third game of the four-game series will be Dominic Leone (3-3, 1.41) in a bullpen outing.

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