OAKLAND -- It’s been one big party for the A’s at the Coliseum over the past two nights.

After celebrating Mike Fiers tossing the 300th no-hitter in MLB history on Tuesday, the A’s got another reason to storm the field when Stephen Piscotty slugged a walk-off home run off Reds reliever Robert Stephenson for a 5-4 victory in 13 innings on Wednesday.

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Coming off a 1-8 road trip, their worst of at least eight games since 2011, the A’s have now won the first two games of a six-game homestand. They seem to be having fun again and playing loose, which is when Piscotty said the club is at its best.

“This team likes to celebrate and have a good time,” Piscotty said. “That’s two games where we got to do that. Hopefully that carries over.”

Piscotty’s home run to lead off the 13th was his fifth of the year and the first walk-off hit of his career, coming on a 2-1 fastball that he roped over the scoreboard in left field. With an exit velocity of 109.5 mph, according to Statcast, it was the hardest-hit ball of the game.

“I’m trying to drive it. I was trying to stick through the middle of the field,” Piscotty said. “I wasn’t sure that it would get up. Thankfully it did.”

A not-so-happy homecoming

Sonny Gray received a warm ovation just before taking the mound for the Reds. It was the right-hander’s first game back at the Coliseum after a memorable run with the A’s from 2013-17 that featured eight scoreless innings vs. the Tigers as a rookie in Game 2 of the American League Division Series and a 2015 All-Star selection.

Gray still has a few friends left on the club, and he caught up with them earlier in the day, but they were none too kind once the game began. He was welcomed back with a two-run homer by Jurickson Profar just two batters into the game and chased in the fifth after surrendering a season-high five walks.

Profar turning it on

Profar’s home run was his fourth of the year and second in as many games, extending his hitting streak to six games. Having also made a terrific catch to preserve Fiers’ no-hitter on Tuesday, Profar has been playing with a confidence that is drawing the attention of A’s manager Bob Melvin.

“He’s getting comfortable both defensively and offensively,” Melvin said. “You look at the numbers from last year and you know it’s only a matter of time. He had some struggles early on, and he’s fighting his way through it.”

A flawless bullpen

In relief of Brett Anderson, who allowed four runs over six innings of work, Lou Trivino, Joakim Soria, Blake Treinen, Ryan Buchter, Yusmeiro Petit and Liam Hendriks combined to allow just three hits over seven shutout innings.

Anderson relies on his cutter

Anderson’s night nearly turned disastrous in the second. Having already allowed four runs in the inning, he walked Eugenio Suarez to load the bases with two outs for Yasiel Puig. With Hendriks warming up in the bullpen, Melvin was going to pull Anderson if he allowed one more baserunner. The lefty got out of the inning by getting Puig to ground out, and he got by the rest of the night with his cutter, a pitch he rarely uses.

Anderson’s repertoire features a sinker, changeup and breaking ball. He threw the cutter three times in his previous start against the Pirates, and upped that to 37 of his 96 pitches on Wednesday night.

The cutter allowed him to give the Reds a different look with more stuff on the outer part of the plate, which led to quicker outs over his final four innings, something he needed as he issued a season-high five walks.

“The walks were embarrassing,” Anderson said. “Too many walks and non-competitive pitches, especially when trying to get a shutdown inning. I started throwing the cutter, and it opened up both sides of the plate, something they hadn’t seen before.”