PHILADELPHIA -- The Philadelphia Phillies' youth movement continued to make strides on Saturday evening against the Oakland Athletics.

It wasn't Rhys Hoskins who powered Philadelphia in its interleague matchup with the Athletics, but rather catcher Jorge Alfaro. The rookie mashed a first-pitch home run into the hedges in center field for a go-ahead two-run shot in the bottom of the sixth inning and the Phillies posted a 5-3 win.

"Any time you play a lengthy game like this, with a rain delay, it's always great when you win," Phillies manager Pete Mackanin said. "When you lose it's terrible."

Phillies righty Victor Arano (1-0) secured his first career win in two innings of relief, and he's yet to concede a run in three major league appearances. Arano has been part of a Phillies bullpen that has shut down opponents to the tune of a 2.03 ERA since Aug. 27, something that Mackanin holds in high regard for the team's recent success.

"They're all contributing and they're all pitching well and that's the reason we're improving because the pitchers are making good pitches," he said.

After falling behind 2-0 early on, a one-hour and 46-minute rain delay bounced Athletics starter Kendall Graveman from the game and the Phillies went to work against Oakland's bullpen.

"Both teams have to do it, but we lost a little momentum, we lost our best starting pitcher so it didn't work out well for us," Athletics manager Bob Melvin said. "We didn't play too terribly well after the delay either."

In relief of Graveman following the delay, righty Chris Smith took over on the mound for Oakland and immediately ran into trouble. Ty Kelly, pinch hitting for Ben Lively, hit a double to left field and second baseman Cesar Hernandez knocked him in to put the Phillies on the board in the bottom of the third.

An error by A's shortstop Marcus Semien extended the inning and put another man aboard for Philadelphia, but Smith got rookie outfielder Nick Williams to fly out to center to end the threat and keep the A's in the lead.

In the bottom of the fourth, Phillies rookie J.P. Crawford got his sixth career RBI when he singled home Odubel Herrera to tie the game at 2. Crawford knocked in Herrera again in the bottom of the eighth with a sacrifice fly to make it 5-2.

"Everybody participated," Mackanin said. "Crawford with a couple of RBIs added on with that sac fly was huge. Odubel stole that base late in the game. ... Alfaro, with the two-run home run to center field, was huge. A lot of good, clutch hitting."

The delay halted the game's momentum and turned into the Phillies favor with the recent dominance from their bullpen.

"What, did we get one hit after the delay?" Melvin asked reporters. "When you don't see somebody, you have to acclimate a little bit but they didn't really know much about our guys either and they had better at-bats and played better after the rain delay than we did."

Athletics first baseman Matt Olson took Lively deep to right field on a 2-2 count to put Oakland on the board in the top of the second inning. Outfielder Boog Powell added a sacrifice fly that scored Mark Canha and the Athletics secured a two-run advantage early in the game.

Herrera continued to get on base and be a catalyst for the Phillies, just as he's done throughout the second half of the season. Herrera connected on a single to right field in the third inning for the first Phillies' hit of the evening. First baseman Tommy Joseph sent a liner right back at Graveman, who snagged it and doubled up Herrera at first for a spectacular end to the inning.

Graveman went two scoreless innings, allowing one hit for the A's.

Lively pitched three innings, surrendering two earned runs for the Phillies.

Simon Castro (1-3) took the loss for Oakland, pitching two innings and surrendering two runs, both of which came on the home run from Alfaro in the bottom of the sixth.

Hector Neris picked up his 21st save of the season for the Phillies, although he surrendered a solo shot to Jed Lowrie.

NOTES: Since Aug. 27, the Phillies' bullpen has posted a 2.03 ERA, which is second in the majors behind only the Cleveland Indians in that span. ... Athletics 3B Matt Chapman leads all rookies in doubles and extra-base hits since the All-Star break with 17 and 31, respectively. ... Since June 1, Phillies OF Odubel Herrera is batting .337, good enough for third in all of baseball trailing Houston's Jose Altuve (.364) and Cincinnati's Joey Votto (.338). ... As 2017 interleague play concludes, A's pitchers haven't recorded an extra-base hit in a game since Joe Kennedy hit a double on June 12, 2007 at Houston.