SAN DIEGO -- The Padres won a bunch of games in empty stadiums last season. They won a bunch more with Petco Park at partial capacity this year, too.

Those wins counted just the same. None of them felt quite like this.

Petco Park opened to full capacity for the first time on Thursday night, and the Padres put on quite a show in front of a packed house, rallying for a wild 6-4 victory over the Reds with Eric Hosmer’s game-tying homer in the bottom of the ninth inning and Victor Caratini’s dramatic walk-off blast two batters later.

• Box score

“It’s just great to be back,” Caratini said afterward. “That’s what you grow up thinking of: You’re in the big leagues, and you have stadiums full of fans. It was really, really great.”

The atmosphere at Petco Park was raucous from the start, and it reached another level when Fernando Tatis Jr. launched a go-ahead homer in the sixth, his 22nd of the season, tying him with Vladimir Guerrero Jr. for the most in the Major Leagues. Manny Machado followed with a solo blast in the seventh, a 433-foot moonshot to the second deck.

But the roller coaster had only just begun. In the top of the ninth, the Reds turned a two-run deficit into a two-run lead against Padres closer Mark Melancon, who had yet to blow a save this season without an automatic runner in extra innings. Tyler Stephenson tied the game with a two-out, two-strike single up the middle, and Jonathan India followed with a two-run homer, putting Cincinnati on top, 4-2.

“Sometimes you need to fight,” said right-hander Joe Musgrove, who worked seven scoreless frames. “Sometimes you need to scratch and claw. … When you win one like this, sometimes it’s what you need to turn things around.”

Hosmer’s two-run homer ignited a Petco Park party that never stopped. Jake Cronenworth followed with a single before Caratini turned on a breaking ball from Reds left-hander Amir Garrett, sending it soaring toward the left-field seats. The noise level in an already-frenzied Petco Park turned deafening, and afterward manager Jayce Tingler posed a rhetorical question:

“Does this happen without the fans?” he mused. “My honest immediate reaction is: No.”

The Padres needed a win like this, to say the least. They returned home Wednesday night after a 1-5 road trip and an ugly sweep in Colorado. They had lost 13 of 17. Meanwhile, the Giants and Dodgers have taken advantage of the Padres’ recent funk to gain some separation in the National League West standings.

Any win would’ve sufficed. But the manner of this victory offered a particular level of catharsis. These were the Padres with World Series aspirations, fighting back from the brink. These were the Padres who had raced out to one of the best records in baseball before their June gloom. And, for the first time since they overhauled their roster into a legitimate contender for the first time in at least a decade, they had a packed house in downtown San Diego to embrace them.

“I don’t know if we do that without the place just kind of rocking throughout the night,” said Tingler. “... Magical finish there. This one feels like more than just a regular win. Now we’ve got to come back and play good baseball tomorrow. That’s how we get this thing going.”

Indeed, the Padres need to get this thing going, and in that regard, their victory Thursday offered multiple layers of positive vibes.

Lately, Machado and Hosmer have struggled as the Padres’ offense floundered. Both authored big-time homers on Thursday night, particularly Hosmer, whose game-tying blast came on the heels of a 6-for-51 start to June. The Padres need their two big-name corner-infielders supporting Tatis in the middle of their lineup, and Thursday night was a perfect indication of what their offense might look like when that happens.

The Padres punched. The Reds punched back. And the Padres’ offense had the firepower to deliver a knockout blow in the ninth.

"What a great baseball game to be a part of,” Reds manager David Bell said. “It felt very similar to a playoff game. … Even though we lost the game, which was obviously disappointing, it was just a great experience, a great game for our team to be a part of.”

Bell wasn’t the only one who felt that way.

“It’s been so long since we’ve had a full crowd in there, I swear to God, it felt like a playoff game,” Musgrove said.

The Padres anticipate hosting a few of those come October. To do so, they’ll need a few more nights like this.