PITTSBURGH -- Starling Marte had a pretty good idea of what pitch was coming and he didn't miss it as he got the Pittsburgh Pirates a step closer to securing home field in the National League wild-card game.

Marte's two-run home run in the bottom of the 12th inning lifted the Pirates to a 6-4 victory over Cincinnati on Friday night, extending the Reds' losing streak to 13 games.

It was the left fielder's 19th home run of the season and third career walk-off shot. He also hit a game-ending homer Aug. 22 against the San Francisco Giants.

Right fielder Gregory Polanco drew a one-out walk off reliever Colin Balester (1-1) and Marte hit the next pitch into the right-field stands as the Pirates (97-63) maintained a two-game lead over the Chicago Cubs (95-65) for the first NL wild card and the right to host Wednesday night's game.

"After he walked (Polanco), I was looking for him to throw a fastball on the first pitch," Marte said. "I knew he didn't want to get behind in the count and I got the pitch I was looking for.

"It's exciting, especially in this game where we're trying to play at home. We play good baseball at home. We want to make our fans happy. We want to play here."

Arquimedes Caminero (5-1) pitched one scoreless inning of relief for the win.

Pirates center fielder Andrew McCutchen had three hits, including a home run. Marte had two hits.

Shortstop Eugenio Suarez had two hits and three RBIs, including a two-run home run for the Reds (63-97), who last lost 13 in a row in 1945. Second baseman Brandon Phillips, right fielder Jay Bruce, left fielder Adam Duvall and rookie catcher Ramon Cabrera had two hits each.

First baseman Joey Votto went 1-for-5 and tied the Cincinnati franchise record by reaching base for the 48th straight game with a third-inning single. Pete Rose set the mark in 1978, a run that included a NL-record 44-game hitting streak.

The Reds built a 4-0 lead in the third inning but couldn't hold it.

"I'm kind of at a loss for words right now," Cincinnati manager Bryan Price said. "Hard-played game, had to exploit most of the bullpen, a lot of guys down there on fumes and just trying to find a way to get through it and put ourselves in a position to win a game."

Both starting pitchers lasted five innings.

Pirates left-hander Francisco Liriano allowed four runs and seven hits with five strikeouts and no walks. Liriano raised his season strikeouts total to 205, surpassing the 201 he had in 2010 with the Minnesota Twins.

Despite his shaky outing, the Pirates won for the 16th time in Liriano's last 17 starts.

"He elevated a number of pitches," Pittsburgh manager Clint Hurdle said. "He wasn't at his best this time."

Reds rookie right-hander Keyvius Sampson gave up four runs on three hits while striking out seven and walked two. The 24-year-old is winless in his last nine starts, going 0-5 in that span.

"I wasn't trying to overdo it, just trying to go out there and trying to attack the zone," Sampson said. "I felt good. Wish we could've got the W, though."

The Pirates pulled into a 4-4 tie with a three-run sixth inning when the Pirates loaded the bases with none out to chase Sampson.

Left-hander Tony Cingrani relieved and walked pinch-hitter Michael Morse to force in a run. Another run scored on first baseman Pedro Alvarez's fielder's choice grounder then shortstop Jordy Mercer tied it with an RBI single.

The Reds took a 4-0 lead with a pair of runs in both the second and third innings.

Suarez hit a two-run home run, his 13th of the season, in the second. An inning later, right fielder Jay Bruce hit an RBI double and Suarez followed with a run-scoring single.

McCutchen drew the Pirates within 4-1 when he led off the fourth inning with his 23rd homer.

"These games are so important," Polanco said. "We had to fight hard to win this one. It feels really good."

NOTES: Manager Clint Hurdle said the Pirates are leaning toward carrying three catchers for Wednesday's NL wild-card game against the Chicago Cubs, meaning rookie C Elias Diaz would serve as the third-stringer behind C Francisco Cervelli and C Chris Stewart. ... Reds LHP Brandon Finnegan (1-2, 5.09 ERA) will face Pirates RHP A.J. Burnett (9-6, 3.15 ERA) on Saturday night in the second game of the three-game series. It could possibly be Burnett's last game, as the 17-year veteran plans to retire at the end of the season and is not scheduled to pitch the wild-card game.