CINCINNATI — Ryan Doumit settled in front of a laptop set up on a folding table in the middle of the clubhouse, reached for the mouse and selected the video of his last swing.

The Pirates catcher clicked on it seven times, replaying the moment when he connected for his first career grand slam. Why so many? Was he looking for a flaw?

‘‘Actually, I was,’’ he said.

Didn’t find any. The Pirates had very few of those on Saturday as they rolled to a 10-2 victory over the Cincinnati Reds behind Doumit’s homer — one of three by Pittsburgh — and Paul Maholm’s seven impressive innings.

The clinching hit came from a player who was supposed to be on the bench.

Manager John Russell planned to play Doumit in the series opener on Friday night, then let him sit out the next day’s afternoon game. When the opener was rained out, Doumit got the chance to play on Saturday and hit his first grand slam since he was in Class A in 2002.

‘‘It worked out,’’ Doumit said. ‘‘I want to play. If I have to wake up and come here, I might as well play. It was a great day.’’

Maholm (1-0) got his first road win since July 22, a stretch of futility that was more a reflection of Pittsburgh’s offense than his pitching. The left-hander gave up just seven earned runs in his previous five road starts, but Pittsburgh managed to score only eight.

The runs weren’t a problem this time, with the Pirates piling up a season high.

Nate McLouth provided more than enough with his two-run homer in the first inning and run-scoring single in the seventh. Pitching with an unaccustomed cushion, Maholm made quick work of Cincinnati hitters, allowing only three hits and one run.

‘‘Nate got the home run, and I knew I had to make those two runs stand up,’’ Maholm said. ‘‘That was my goal.’’

Pittsburgh pulled away in the ninth, when Doumit hit his grand slam off Mike Lincoln and Adam LaRoche followed with his first homer of the season. The game then ended with an exasperating play for the Reds — Jay Bruce got doubled up at first base on Ramon Hernandez’s long flyout.

The Reds fell to 1-3 for the first time since 2003, their first season in Great American Ball Park.

‘‘We’ve just got to play better heads-up baseball — play with our heads up, not with our heads down,’’ manager Dusty Baker said.

Johnny Cueto (0-1) struck out nine batters in six innings, but gave up five extra-base hits — three doubles, a triple and McLouth’s second homer of the season.

The Reds’ defense prevented the Pirates from pulling away in the third. Bruce threw out McLouth at the plate as he tried to score from second on Doumit’s single to right. Willy Taveras saved another run by catching LaRoche’s fly ball while slamming into the wall in center for the final out of the inning.

All that did was slow ’em down.

The Pirates had three more extra-base hits in the fourth. Consecutive doubles by Brandon Moss and Jack Wilson made it 3-0, and Nyjer Morgan hit a triple to center that tipped off the end of Taveras’ glove as he tried to make an over-the-shoulder catch.

Morgan walked in the seventh, stole second and came around on McLouth’s single, bowling over Hernandez with a lowered forearm as he scored for a 5-0 lead. Morgan had three hits and a pair of steals, scoring twice.

The Pirates had some run-saving defense of their own. Moss threw out Joey Votto when he tried to score in the fourth inning. Votto, the Reds’ top hitter so far, tore a big hole in the left knee of his pants during his slide and got up limping, but stayed in the game.

The way Maholm was pitching, the Reds weren’t going to get many more chances.

‘‘His ball does a lot more than people think,’’ Votto said. ‘‘He’s smart. He puts the ball where he wants it, and he’s aggressive.’’

Notes: Coming into the game, McLouth was only 1-for-14 with a homer. … Maholm has given up two earned runs in 13 2-3 innings spanning two starts this season. … Reds RHP Micah Owings had a pinch-hit double in the eighth. Owings originally was scheduled to pitch on Saturday, but the rainout prompted Baker to skip him.

Pirates 10, Reds 2

Saturday’s Game

Pittsburgh Cincinnati

ab r h bi ab r h bi

Morgan lf 4 2 3 1 Tavers cf 3 0 0 0

FSnchz 2b 5 1 1 0 HrstnJr lf 4 0 0 0

McLoth cf 3 2 2 3 Votto 1b 3 0 0 0

Doumit c 5 1 3 4 Phillips 2b 3 2 2 0

AdLRc 1b 5 1 1 1 Encrnc 3b 3 0 1 0

AnLRc 3b 5 0 0 0 Bruce rf 4 0 1 2

Moss rf 4 1 1 0 RHrnandz c 4 0 0 0

JWilson ss 3 1 1 1 AlGnzlz ss 3 0 0 0

Mahlm p 3 0 0 0 Cueto p 1 0 0 0

Grabow p 0 0 0 0 DMcDn ph 1 0 1 0

Hinske ph 0 1 0 0 Herrer p 0 0 0 0

JChavz p 0 0 0 0 Burton p 0 0 0 0

Owings ph 1 0 1 0

Lincoln p 0 0 0 0

Totals 37 10 12 10 Totals 30 2 6 2

Pittsburgh 200 200 105 — 10

Cincinnati 000 000 101 — 2

E—Phillips (1). DP—Cincinnati 1. LOB—New York 5, Cincinnati 7. 2B—Church 2 (3). HR—Votto (2). SB—Encarnacion (1). CS—J.Reyes (1). S—Arroyo. SF—Delgado, Cora, Phillips

IP H R ER BB SO

Pittsburgh

Maholm W,1-0 7 3 1 1 2 3

Grabow 1 1 0 0 0 2

J.Chavez 1 2 1 1 1 0

Cincinnati

Cueto L,0-1 6 8 4 4 1 9

Herrera 1 1 1 1 1 3

Burton 1 0 0 0 0 0

Lincoln 1 3 5 5 3 0

Umpires—Home, Ed Montague; First, Jerry Layne; Second, Tony Randazzo; Third, Chris Guccione.T—2:49. A—22,276 (42,319).