Rusin made an emergency start and did well on Tuesday night before the Cincinnati Reds rallied against the bullpen for a 2-1 victory that ended their nine-game losing streak.
"I know it didn't hurt me," the 28-year-old pitcher said. "I've just got to go from there."
Colorado switched starters before the game, deciding to give left-hander Jorge De La Rosa a couple extra days to let a cut on his pitching hand heal. Rusin, who made 20 starts for the Cubs from 2012-13 before being moved into the bullpen last season, was called up from Triple-A Albuquerque to fill in.
Rusin gave up Billy Hamilton's RBI single and four hits overall, leaving with the scored tied 1-1.
"It's a confidence booster," Rusin said. "I've been throwing well in Triple-A, but not like this. I hadn't been getting past the sixth. To get into the seventh inning was a confidence boost."
Manager Walt Weiss was impressed with Rusin, who may have made himself the top option for the next time a starter is needed.
"Rusin was outstanding," Weiss said. "He had a good fastball with late movement. His secondary stuff was good. He was in control all the way."
Kristopher Negron sacrificed, and Schumaker hit an opposite-field liner that landed just inside the left-field foul line to end it.
Players piled out of their dugout for a wild celebration near second base after Schumaker ended the Reds' longest slump since they dropped 11 straight under manager Jack McKeon in 1998.
Cincinnati had the second-longest losing streak in the majors this season, trailing Colorado's 11-game slide from April 28 to May 13.
Michael Lorenzen gave up two hits in seven innings, including Nick Hundley's fifth homer, in his return to the rotation. The right-hander started three games and was moved to the bullpen for two appearances before making another start on Tuesday.
Colorado optioned reliever Yohan Flande to Triple-A to open a roster spot for Rusin. Flande was called up May 14 and made three appearances, allowing six runs in 7 1/3 innings.
Several hundred dogs were in the stands with their owners for the Reds' second Bark in the Park pet promotion.
ANOTHER RAINY NIGHT
Rain fell intermittently throughout the game, but there were no delays. The Reds have had six rain delays and one rainout at Great American Ball Park this season. The Rockies have had four games rained out, matching the most in club history.
Rockies: Carlos Gonzalez was back in right field after sitting out Monday's game with a stomach illness. He went 0 for 3 with a walk.
Reds: An MRI found inflammation in Johnny Cueto's pitching elbow but no significant injury. He will miss at least one more start. ... 2B Brandon Phillips was out of the lineup after aggravating a sore toe on his left foot.
Rockies: Kyle Kendrick (1-6) tries for his first win since he beat the Brewers on opening day. In his last eight starts, he's 0-6 with a 6.99 ERA.
Reds: Mike Leake tries to pull out of his slump. He's 0-2 in his last two starts, allowing 14 runs and four homers in nine innings.
Follow Joe Kay on Twitter: http://twitter.com/apjoekay