CINCINNATI (AP) — The Reds gave up six home runs and lost home-field advantage for the wild-card playoff. They had to scramble their postseason rotation because of an injury

Uh-oh.

Neil Walker hit two of Pittsburgh’s six homers — its biggest power surge in six years — and the Pirates clinched home-field advantage for the NL’s wild card playoff game by beating Cincinnati 8-3 Saturday.

Pittsburgh will host the Reds on Tuesday night in the Pirates’ first playoff appearance in 21 years. They went 50-31 at PNC Park, the third-best home record in the NL.

The Reds needed to win two of the three games this weekend to get the playoff at Great American Ball Park.

Couldn’t do it.

“It’s disappointing, but you’ve got to get over it,” manager Dusty Baker said. “Teams have won championships with their backs to the wall, like San Francisco last year. If that’s what you’ve got to do, that’s what you’ve got to do.”

Last season, the Giants won three at Great American Ball Park to advance, eventually winning the World Series. The Reds are in the playoffs for the third time in four years. They’ve failed to get past the first round the last two times.

Cincinnati will go with Johnny Cueto (5-2) in the one-game playoff against left-hander Francisco Liriano (16-8). Mat Latos was on schedule to start for Cincinnati, but Baker said he’s developed a sore arm.

And he’s not the only one hurting. Bronson Arroyo (14-12) had back spasms before the game on Saturday. Homer Bailey had a sore leg after his start during a 4-1 loss on Friday night.

“Latos’ arm is barking, and we’re hoping to give him a couple of extra days to be ready for Atlanta,” Baker said, looking ahead to the next round. “Bronson’s back was sore today. Homer’s leg was sore yesterday. We’re hurting.”

The Pirates won five of nine games against the Reds at PNC Park this season.

Pittsburgh hit five homers off Arroyo, who had never given up that many in a game in his career. Walker homered twice off the right-hander, Andrew McCutchen and Pedro Alvarez also hit solo homers, and Marlon Byrd had a two-run shot that ended Arroyo’s outing in the fifth and made it 6-3.

Arroyo said his back started bothering him before the game.

“It locked up right before the game,” Arroyo said. “I was in the tunnel. It was like I was being stabbed in the ribs and I couldn’t swivel from side to side.

“I don’t think it had much to do with the game. You can’t leave balls in up the zone in this ballpark against that lineup and get away with it.”

Prospect Andrew Lambo hit his first homer off Logan Ondrusek, the first time the Pirates had six in a game since Aug. 22, 2007 at Colorado.

Pirates starter Charlie Morton also struggled, leaving with one out and the bases loaded in the fifth. Vin Mazzaro (8-2) fanned Zack Cozart and retired Ryan Hanigan on a fly ball as the slumping Reds left the bases loaded for the second time in the game.

Cincinnati stranded 11 runners overall.

The Ohio River rivals have met five times in the playoffs — 1970, 1972, 1975, 1979 and 1990, when the Reds won their last World Series title. The Reds are 13-7 against the Pirates in the postseason. Pittsburgh has played the Reds more than any other team in the playoffs.

The Reds have gone into a deep slump at a very bad time. They’ve lost four in a row since clinching a playoff spot with a 3-2 win over the Mets on Monday night, scoring a total of six runs.

Walker and McCutchen hit back-to-back homers in the third for a 2-0 lead. Brandon Phillips had an RBI single and Jay Bruce followed with a two-run double for a 3-2 lead in the third, Cincinnati’s first lead since Monday.

And it didn’t last long.

Alvarez led off the fourth inning with a first-pitch homer, tying it at 3. Alvarez’s 36th homer gave him 100 RBIs. Walker hit his career-high 16th homer in the fifth inning — the first multihomer game of his career — and Byrd’s two-run shot ended Arroyo’s outing.

Lambo’s pinch-hit homer let the Pirates tie the record for most by a visiting team at Great American Ball Park, which opened in 2003.

NOTES: Alvarez is the first Pirates third baseman to drive in 100 runs since Aramis Ramirez drove in 110 in 2001. His 36 homers are a club record for a third baseman. … Byrd had three hits for the second straight game. … Philips fouled a pitch off his left shin in the fifth inning, raising a welt. He singled and left for a runner. X-rays were negative. … Joey Votto walked three times, moving him ahead of Joe Morgan’s previous club record for a season. Votto has walked 135 times.

———

Follow Joe Kay on Twitter: http://twitter.com/apjoekay