CINCINNATI -- With a thin bench and first baseman Joey Votto nursing a knee injury, Jay Bruce was asked to do something for the first time as a pro Monday night: play first base.

"It was very, very stressful," said Bruce, normally the Cincinnati Reds' right fielder. "Hopefully that will lessen. It's something I don't want to prolong. Hopefully we get Joey back healthy. But if I'm going to play first base, I want to be good at it. I'll do what I need to do to help the team win."

Bruce made a couple fine of defensive plays but also committed a run-scoring error. He compensated by belting a two-run home run in the eighth inning, and center fielder Billy Hamilton added a career-high four RBIs, lifting the Reds to a 9-3 victory over the Chicago Cubs in the opener of a five-game series Monday night at stormy Great American Ball Park.

"Thankfully I drove in more (runs) than I let in," Bruce said.

First baseman Anthony Rizzo snapped an 11-game homerless skid with his 18th round-tripper, and left fielder Chris Coghlan went 4-for-5 with two doubles for Chicago (38-49), which went 2-for-15 with runners in scoring position and left nine on base.

"I think for us the storyline is we had some opportunities to score some runs today," Cubs manager Rick Renteria said. "We had some guys in scoring position, and we left a lot of guys out there."

Reds starter Mike Leake (7-7) threw seven innings and allowed three runs (two earned) on seven hits with a walk and seven strikeouts. It was his 11th quality start this season.

"The first-batter-of-the-inning management wasn't a strength tonight, but pitching with runners on base was," Reds manager Bryan Price said of Leake. "He really did a good job. (Rizzo's homer) took a little sweetness out of the outing for him, but he gave us a chance to win, and we were able to extend the lead and put it away."

In addition to Bruce's move, Cincinnati (46-42) made another defensive swap that paid dividends.

Skip Schumaker, subbing for Bruce in right field, ended the sixth inning when he caught second baseman Darwin Barney's fly ball, then threw out Welington Castillo attempting to score.

"You weaken the lineup the least moving me into first, because we have some very capable outfielders," Bruce said. "Skip made a great play."

Bruce's 423-foot, two-run home run off James Russell put Cincinnati ahead 6-3 in the seventh. It was his ninth home run of the season.

Hamilton, who is batting .349 with runners in scoring position, tripled off Blake Parker with the bases loaded in the eighth, driving in three runs.

Cubs right-hander Edwin Jackson (5-9) walked Hamilton on four pitches to begin the game. Hamilton later scored the game's first run on second baseman Brandon Phillips' sacrifice fly.

Coghlan doubled with one out in the third but was left stranded moments before a storm rolled in and caused a 21-minute rain delay.

All eyes were on Bruce, who earned a loud ovation for fielding right fielder Nate Schierholtz's hard grounder down the first base line for an unassisted putout ending the fourth inning with the tying run on second.

However, in the fifth, Rizzo's grounder skipped past Bruce for an error, and Coghlan scored from third to tie the game at 1-1.

"It's a play I expect to make," Bruce said. "I really felt bad missing that ball down the line. It was a tough play, but I should've made it."

Jackson continued to roll following the rain delay, retiring 13 consecutive batters. He ran into trouble in the fifth when consecutive RBI singles by Hamilton and third baseman Todd Frazier put Cincinnati ahead 3-1.

"It's just a matter of making a pitch with two outs," Jackson said. "That's pretty much what it boils down to. I'm a pitch away from being out of that inning."

NOTES: Reds 1B Joey Votto underwent an MRI exam Monday to determine the extent of his nagging quadriceps injury. Manager Bryan Price said the club would wait for the results before determining what to do next. ... Chicago manager Rich Renteria texted congratulations to former Cubs RHP Jeff Samardzija, who won his debut with the Oakland A's on Sunday. "Anytime you have anybody that you've been associated with, quite frankly, and the circumstances change as far as them being a part of our club, it was good to see him do well," Renteria said. ... Reds LHP Aroldis Chapman was available to pitch Monday after tweaking a hamstring in the outfield before Sunday's game. He did not get into the series opener against the Cubs. ... Cincinnati agreed to terms with its top draft choice, University of Virginia RHP Nick Howard.