(AP) -- Bronson Arroyo pitched eight dominant innings to win a matchup of struggling pitchers and Jeff Keppinger had a career-high five hits, lifting the Cincinnati Reds over the New York Mets 7-1 Saturday for a split of their day-night doubleheader.

In the opener, Carlos Beltran hit a bases-loaded triple and drove in five runs to back Johan Santana's first home win for the Mets in a 12-6 victory. Carlos Delgado and Brian Schneider hit New York's first back-to-back homers of the season.

Ken Griffey Jr. had two hits and an RBI in the nightcap, a makeup of Friday night's rainout, but remained stalled in his bid to become the sixth player with 600 home runs. He is homerless in 59 at-bats.

Griffey missed No. 598 by inches in the opener when he hit a drive off the top of the wall for a two-run double that earned him a start in the second game.

The Reds outhit the Mets in the loss, 15-12, and the win, 14-4 -- but also got solid pitching and defense in the nightcap. They broke it open in the ninth thanks to some sloppy fielding by New York and Scott Hatteberg's third RBI of the game.

That prompted angry Mets closer Billy Wagner to knock over a water cooler in the dugout after he was pulled. Wagner entered in the ninth to get some work in and try to keep it close.

Arroyo (2-4) struck out the side in the first and immediately put to rest any thoughts of a repeat of his awful outing a week ago, when he gave up seven runs in the shortest start of his career -- 1 1-3 innings.

The Mets loaded the bases with one out in the second but Arroyo struck out Ramon Castro, and pitcher Mike Pelfrey (2-3) flied out to right fielder Griffey, who made a basket catch on the run.

Griffey had an RBI single one out after Ryan Freel doubled leading off the game. The Mets tied it in the third when David Wright hit a run-scoring single one out after Jose Reyes doubled.

The Reds took the lead in the sixth on Hatteberg's double, which scored Keppinger. Hatteberg drove in Keppinger again in the eighth with a single off Duaner Sanchez. Paul Bako added an RBI single in the eighth to make it 4-1.

The Reds added three unearned runs against Wagner in the ninth with help from errors by Wright at third base and Delgado at first. Keppinger, Hatteberg and Bako had RBIs.

Baffled by his 8.63 ERA entering Saturday despite being healthy, Arroyo struck out the side again in the seventh, then fanned Reyes to start the eighth. The right-hander finished with nine strikeouts and two walks.

Francisco Cordero worked a perfect ninth to complete the four-hitter.

In the opener, Wright broke out of a 1-for-13 slump with two hits and three runs, helping the Mets score 12 times for the second consecutive game. Moises Alou had two RBIs and New York began a seven-game homestand against last-place teams.

Manager Willie Randolph started Santana in the opener instead of Pelfrey, Friday's scheduled starter, because "I like to get my best going first," he said. Santana matched a career high by giving up 10 hits, though he never was in serious trouble until the sixth, when he needed 38 pitches to get out of the inning.

"Allergies have been bothering me, but it's no excuse," Santana said. "My eyes, my nose, I battled through and we were able to win. ... When I see my team hitting balls and scoring runs you feel good."

Pelfrey vastly improved on his last two starts in which he gave up five runs and 13 baserunners in each. He worked six effective innings Saturday, allowing eight hits and two runs. He struck out three and walked one.

Santana (4-2) allowed Edwin Encarnacion's eighth homer in the opener.

"The game should have been a lot closer than it was," Reds manager Dusty Baker said.

Beltran's triple off reliever Mike Lincoln in the sixth made it 10-3. The slugger had an RBI single in the third and a sacrifice fly in the fifth for his first RBIs since April 26.

Delgado homered off Lincoln in the seventh, his fifth, and Schneider followed with his first of the season.

After beginning the day with a .216 average, Delgado had three hits from the No. 7 spot in the order, missing the cycle by a triple. It was the first time he batted that low since Sept. 30, 1995, with Toronto against the New York Yankees, according to the Elias Sports Bureau.

Matt Belisle (1-3) gave up six runs -- five earned -- and seven hits in five innings. He threw a wild pitch that let a run score and committed a two-base throwing error that led to two runs in the fifth.

Delgado batted fifth against Arroyo and extended his hitting streak to eight games with a first-inning single.