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Thick, marine air rolls over Petco Park at night, around the third inning most games, and forms an invisible wall above center field. Hitters curse it. Pitchers love it. Baseballs die when they run into it. Home runs in the latter innings rarely occur, and when a ball manages to clear the fence in right-center field, it tends to creep over.

Saturday night, in a pivotal moment of the Nationals’ 4-3 loss against the San Diego Padres, Ian Desmond’s blast doubled as a clutch home run and an incredible feat. Down a run in the seventh, with a man on second, Desmond launched a ball over the fence, over a back wall and into a shrub. Center fielder Cameron Maybin stopped in his tracks, stunned. The Nationals had taken the lead, and Desmond had hit a ball 437 feet through the syrupy San Diego night air, the longest ball hit this season at Petco Park.

“I’ve been coming here a long time,” Nationals hitting coach Rick Schu said. “I’ve never seen anybody hit one that far, especially at night.”

Desmond’s team-leading 12th homer may have been his biggest this year, in two ways. It sent the Nationals ahead in the seventh inning. And it had people comparing his power to that of some of the league’s strongest sluggers.

“I’ve only seen a couple balls hit that far” at Petco at night, Kevin Frandsen said. “And they were by Bonds.”

Desmond continued his power surge Sunday afternoon, launching a two-run homer to the left of center field in the second inning. Desmond’s second homer in as many days put him on a 162-game pace for 34 home runs this season, which would be the most by a shortstop since Miguel Tejada hit 34 in 2004. No shortstop has even hit 30 since 2011.

None of his blasts have been more impressive, though, than Saturday night’s. One NL scout who has watched games at Petco Park for years was asked who he’d seen homers to that shrub at night. “The big dogs,” he said. “Guys with big, hairy power. Bonds. Adrian [Gonzalez] put a couple balls there. [Paul] Goldschmidt has gone there a couple times. There’s no doubt [Giancarlo] Stanton could. Not many guys.”

Desmond had little to add when asked about the homer Sunday morning. He grinned, flexed his left biceps and walked away.

“You don’t see too many balls go there,” Jayson Werth said. “When I played here in this division for two years, I hit balls good to center that got caught right at the wall. For him to go right of center, that’s just that much farther. Anywhere left of center is a lot different than right. For him to go there is impressive.”

Nationals bench coach Randy Knorr planned to go ask Maybin how often he had seen the ball in the shrub. He assumed it would not be many. “It reminded me of a young Randy Knorr,” Knorr said with a chuckle. In 738 career plate appearances, Knorr hit 24 home runs.