CINCINNATI -- The Reds really tried to keep Tony Santillan around for one more out to give their starting pitcher a chance to win his big league debut on Sunday afternoon. Santillan was unable to get the third out against the Rockies in the fifth inning, but a beleaguered Cincinnati bullpen -- ranked last in the Majors in ERA -- proved something more important.

Reds relievers showed they could hold a lead in a close game without the injured Tejay Antone. Five relievers combined to strike out eight over 4 1/3 innings with one run and one hit allowed for a 6-2 win and a three-game series sweep at Great American Ball Park.

“This was a very big game for us," said Lucas Sims, who pitched a perfect final two innings.

"I think we’re at a point where we came together as a group and realized, 'It can either go one or two ways at this point, boys. Let’s figure out something. Let’s come together. Let’s make this mean something. Let’s pass the baton and let’s get this thing rolling.’”

At 32-31, Cincinnati is above .500 for the first time since April 21. The big hits were a two-run home run by Eugenio Suárez in the second inning that gave Santillan a 3-1 lead, and a two-run chopped double by Jesse Winker through a drawn-in infield in the three-run seventh.

Called up from Triple-A Louisville to replace the injured Sonny Gray, Santillan pitched 4 2/3 innings and gave up one earned run with five hits and four walks, while striking out five.

“It was fun to be here. It was the dream come true, obviously. I enjoyed every minute of it, for sure," said Santillan, the Reds' 2015 second-round Draft pick and ranked as the organization's No. 9 prospect by MLB Pipeline.

Santillan gave up hits to his first two batters of the game and trailed, 1-0, following Charlie Blackmon's sacrifice fly to left field.

Colorado, which was 0-for-9 with runners in scoring position and stranded 12, had Santillan in trouble multiple times. The right-hander had runners on the corners and one out and left them stranded in the second inning. With the bases loaded in the top of the third inning, Santillan received a mound visit from catcher Tucker Barnhart and pitching coach Derek Johnson. Then when he had C.J. Cron in a 3-1 count, the crowd of 18,268 fans came alive in support.

Santillan escaped with Cron's flyout to right field.

“Absolutely, it was one of my favorite moments today," Santillan said. "It was the first time that I’ve played in front of that many people, ever. When the crowd came alive, it was pretty awesome, a very surreal moment."

With two outs in the fifth inning and heavy rain falling, Santillan was one strike from qualifying for a win, but he lost Brendan Rodgers to a walk and then walked Cron to load the bases. Manager David Bell made the move to rookie Ryan Hendrix.

"For a first start, it doesn't get much better than that. I thought he did a great job," Bell said.

Hendrix ran up a full count to Dom Nunez but struck him out with a slider in the dirt to end the threat, before letting out a big yell as he left the mound.

"It was awesome, man," said Hendrix, who was awarded the victory. "Especially having to come in with the rain just pouring down. Tough to kind of grip the ball, but I was going to get it done for Tony either way in his debut. I’ve been with him all through Minor League ball, so it’s cool getting to come in and getting the punchout right there."

Bell still had four more innings to piece together. Brad Brach struck out his first two batters before issuing a walk in the sixth. Summoned to face the lefty-hitting Blackmon, struggling left-hander Amir Garrett took over and struck him out on three pitches.

"No question Brad could've gotten it done, but we felt like shutting it down right there using Amir to get out of that inning," Bell said. "[It] kind of shifted the game for us right there."

Heath Hembree was given the seventh inning and allowed Ryan McMahon's solo home run to right field and a two-out walk. After Winker helped provide insurance runs, Sims retired all six batters he faced. He is the best reliever in the bullpen after Antone went on the 10-day injured list on Friday with right forearm inflammation.

"Whether someone is struggling or injured or something happens, it’s really just that attitude of, ‘It’s time to step up.’ Go out there and do your job," Sims said. "Do it for the 25 other guys on the team. Play your role and make it mean something."

Cincinnati is enjoying the moment after winning 10 of its last 13 games as it prepares for a big nine-game road trip. It begins with three games at National League Central leader Milwaukee.

"It’s great. It’s amazing," Winker said. "It just shows you the caliber of the team we are. We got a lot of baseball ahead of us to play, so I feel like we are headed to where we want to be with a lot of season left to go."