SAN FRANCISCO -- For most of the afternoon, it looked like the Giants would again be haunted by poor defense.

Rookie third baseman Casey Schmitt committed a costly defensive miscue that allowed the Guardians to score two unearned runs to cap a four-run rally in the first inning, but the Giants overcame the early deficit and rallied for a stirring 6-5 walk-off win in 10 innings in Wednesday’s series finale at Oracle Park.

• Games remaining (16): at COL (4), at AZ (2), at LAD (4), vs. SD (3), vs. LAD (3)
• Standings update: The Giants (75-71) are a half-game behind the Reds (76-71) and D-backs (76-71) for the third and final National League Wild Card spot. They also have the same record as the Marlins (75-71) in the race, but San Francisco holds the tiebreaker by virtue of a better intradivision record.

Down 5-1, the Giants pulled within three on Wilmer Flores’ RBI single in the seventh and then tied the game on J.D. Davis’ three-run homer off Guardians reliever Eli Morgan in the eighth.

After closer Camilo Doval worked a 1-2-3 top of the 10th to strand automatic runner Josh Naylor, the Giants completed their comeback behind LaMonte Wade Jr.’s sacrifice fly off Xzavion Curry.

Davis and Brandon Crawford drew back-to-back walks to load the bases for Wade, who lifted a fly ball to left to score automatic runner Patrick Bailey from third and end the game. It was the second walk-off RBI of the series for Wade, who also delivered a walk-off single in Monday night’s 5-4 win.

“When we get into those very close battles, we don’t give up,” manager Gabe Kapler said. “I think we’re going to look back at this game at the end of the season and believe that it was very meaningful.” 

With the win, the Giants improved to 11-3 (.786) in extra innings -- the best winning percentage in the Majors -- and capped a 5-1 homestand that got them back on track after they lost six in a row to the Padres and Cubs. They’ll aim to sustain that success as they head to Denver to kick off their final regular-season road trip of the year on Thursday night at Coors Field.

“I think it’s exactly what we needed,” said Davis, who delivered the Giants’ first three-run homer since July 18. “We went through a tough stretch of facing a lot of good teams. Coming off that series loss against the Cubs, that was a big stinger, but to come home and make a statement, I think that’s huge for us just to get some momentum and get some positivity going back on the road.”

The Guardians wasted little time jumping on prized left-hander Kyle Harrison, who issued a leadoff walk to Steven Kwan before surrendering a towering two-run blast to José Ramírez in the first. Naylor followed with a single and advanced to third on another one-out knock by Andrés Giménez, who later stole second to put a pair of runners in scoring position with two outs.

Harrison, who didn’t have as much life on his fastball at the beginning of his outing, nearly escaped further damage after inducing a routine grounder to third from Gabriel Arias, but Schmitt fired a low, one-hop throw that skipped past Davis at first base, bringing home both runners and sinking the Giants into a 4-0 hole.

Despite vowing to improve their defense over the offseason, the Giants lead the Majors with 101 errors, one more than their total from last year. They committed five errors in this three-game series alone, resulting in seven unearned runs for the Guardians. 

“We want to make as few errors as possible,” Kapler said before the game. “Making a lot of errors is not something that we’re going to be proud of or try to discount or act like it doesn’t exist. It does exist. I think on the other side, I feel like we’ve made more plays to protect our pitcher than we did last year. I think our outfield defense has been improved at times. I don’t think we’ve played the type of defense that championship teams need to play here, and I think that we have to keep driving towards that level of defense.”

The 22-year-old Harrison needed 33 pitches to get through the first, then gave up another run in the second after Kwan singled, stole second and scored on Naylor’s RBI single. The stressful innings ultimately expedited his exit, as he departed after throwing 82 pitches over four innings, giving up five runs (three earned) on seven hits while walking one and striking out three.

Fellow lefty Alex Wood replaced Harrison in the fifth and gave the Giants a chance to rally by holding the Guardians to three hits over four shutout innings.

“He’s the man,” Harrison said. “He kept us in the ballgame. Him, [Tyler Rogers] and [Doval], those guys locked it down.”