CINCINNATI -- With Marlon Byrd on the disabled list, the Cincinnati Reds are looking for help in left field. Even catcher Devin Mesoraco is rehabbing his hip injury as a left fielder.

On Monday night, Ivan De Jesus Jr.’s number was called.

"First time in my life playing left field," he said. "I got some extra work in the outfield early. I felt really comfortable out there."

De Jesus Jr. appeared comfortable at the plate, too, belting his first major league home run, a two-run shot in the sixth, lifting the Cincinnati Reds to a 6-4 victory over the Philadelphia Phillies in the opener of a three-game series Monday night at Great American Ball Park.

With the score tied 3-3, De Jesus, who was promoted from Triple-A Louisville on Wednesday, launched a 1-1 pitch from Phillies left-hander Cole Hamels into the left-field seats to put Cincinnati (25-31) ahead to stay.

De Jesus Jr., who went 2-for-4 with a double, homer and two RBIs on Monday, earned a beer shower from teammates after the game. He also was given a souvenir -- his first home run ball.

"I didn’t get the ball from my first hit (in 2011)," he said. "They say it got lost. But, it’s not about the home run. The big thing is we won today."

Hamels (5-5) has dominated the Reds for much of his career, but he didn't fare as well on Monday, allowing five earned runs and eight hits over a season-high 120 pitches in six innings.

"It's major league baseball, you're not going to have the best luck all the time," said Hamels. "No matter what the circumstances, you've got to try to get through it."

Shortstop Zack Cozart added a solo homer off right-hander Justin De Fratus in the eighth for Cincinnati, which now has split four meetings this season with the Phillies (22-37) after a pair of heart-breaking losses last week at Citizen's Bank Park.

Cozart went 3-for-4 with a double, homer and two RBIs on Monday night.

Reds starter Mike Leake (3-4) allowed three earned runs and 10 hits in six innings for Cincinnati and got the victory.

"I’m really proud of him," said Reds manager Bryan Price. "Going against a familiar lineup. Mike did a terrific job without his best stuff, from a crispness perspective."

Closer Aroldis Chapman allowed a run to score in the ninth on a wild pitch. But he struck out second baseman Chase Utley, who represented the tying run, to finish off his 11th save.

Third baseman Maikel Franco continued his hot-hitting for the Phillies, going 3-for-4 with a double.

Leake, who took a no-hitter into the seventh in his start against Philadelphia on Wednesday, allowed three hits in the first inning on Monday, including a double to leadoff batter Ben Revere.

The Phillies right fielder scored on first baseman Ryan Howard's double to the wall in center, making the score 1-0.

Hamels entered Monday's game with a 9-0 record and 1.59 ERA in 13 career starts against Cincinnati.

The first three Reds batters reached base against Hamels on Monday, but he allowed just one run on third baseman Todd Frazier's RBI single.

Center fielder Billy Hamilton's speed created an odd run for Cincinnati in the second inning.

Hamilton singled with two outs, then stole second and third.

Brandon Phillips walked on ball four in the dirt. Thinking the Reds second baseman had swung and missed, Phillies catcher Carlos Ruiz threw unnecessarily to first to complete the strikeout. And Hamilton alertly slid home with the Reds' second run.

It was not recorded as a steal of home because Hamilton didn't start running until Ruiz made his throw.

"With Hamilton on the bases, you've really got to be alert on what he was doing," Phillies manager Ryne Sandberg said.

Ruiz atoned for his mental blunder with a two-run single in the fourth, tying the score 3-3.

But, the Re