DENVER -- Not many starting pitchers would identify Coors Field in Colorado's mile-high thin air as the ideal place to make a Major League debut. On Tuesday, Reds starter Brandon Williamson was only the 10th pitcher to debut at the spacious ballpark where offenses often go wild.

“I tried not to think about it," Williamson said. "You go in there thinking, ‘Oh man, this is a bang box.’ A little negative thought. But you don’t care where your debut is. You just want to get up here.”

Williamson made his first start a superlative one during a no-decision in a 3-1 win over the Rockies. The left-hander, who is ranked as Cincinnati's No. 10 prospect by MLB Pipeline and was called up from Triple-A Louisville, gave up two hits over 5 2/3 innings.

"It can be much more difficult in this ballpark, and it can’t go much better than that. Brandon was outstanding," Reds manager David Bell said.

Williamson opened with Charlie Blackmon's leadoff single but erased him when Jurickson Profar grounded to shortstop for a double play.

"I thought right there, it just settled Brandon in," Bell said. "He was able to roll after that."

The second hit came after Williamson retired 14 batters in a row. It was a one-out solo homer to right field by Ezequiel Tovar on a 2-1 fastball that drifted over the plate to make it a 1-0 game. That accounted for his lone earned run while walking two and striking out six.

Williamson threw an efficient 72 pitches (47 strikes) -- including 56 through his first five innings -- to help a worn-down bullpen.

"I looked up in the fifth inning and was like, ‘Whoa, 56 pitches. Let’s go nine,'" Williamson joked.

Save for Spring Training bullpen sessions, catcher Curt Casali hadn't worked with Williamson before and kept his message simple.

"I just wanted to express how cool it is that he finally did it and enjoy every moment of it. We sprinkled in a little scouting when we could," Casali said. "I always do my homework, so I tried to help him as best as I can, but 5 2/3, one run at Coors Field, yeah, sign me up."

Williamson featured five different pitches but leaned most on his cutter, a pitch he only brought back into his repertoire a few weeks ago.

"I was having trouble getting a good grip, and my cutter is the pitch when I don’t necessarily feel the ball real well, I can still throw it effectively," he said.

Opposite Williamson, former Red Chase Anderson pitched five scoreless innings for Colorado. After he departed, Nick Senzel hit a first-pitch offering from reliever Peter Lambert in the sixth inning for a two-out, two-run homer that got Williamson off the hook.

“[Williamson] threw unreal. I wanted to get him a couple of runs," Senzel said.

Williamson, 25, hadn't posted great numbers in the Minors since he was acquired with Jake Fraley and Justin Dunn in the March 2022 trade that sent Jesse Winker and Eugenio Suárez to the Mariners.

In 27 starts at Double-A Chattanooga and Louisville last season, Williamson was 6-7 with a 4.11 ERA and pitched through shoulder pain while his walk rate soared and strikeout rate dwindled.

The shoulder pain was gone, but overall numbers in 2023 weren't better as Williamson was 2-4 with a 6.62 ERA in eight starts for Louisville. But things started clicking recently, beginning with a bullpen session late last month.

"I was just like, ‘Why do I do anything at a lesser level than 100% right now? I feel great. Why not?’ I just started throwing the ball as hard as I could," Williamson said. "Everything sharpened up. I was like, 'Let’s use this in a game,' and started rolling."

In the subsequent start at Iowa on April 29, Williamson was clobbered for eight runs in one-third of an inning.

"The worst start of my life. I felt fantastic. I thought I was going to dominate," Williamson said.

In the two starts after that, Williamson rebounded and struck out a combined 11 batters over 11 2/3 innings while allowing four earned runs. His confidence was back. 

"I think it was more so my health was where I wanted it to be. I could attack and let everything go, and not ever have to wonder about anything," he said. "Once I started to just rip every pitch I’m throwing, then that kind of builds, builds and builds. It took a couple of weeks to snowball and get downhill."

Shortly before facing Colorado with about 30 friends and family at the ballpark, Williamson exchanged text messages with best friend and injured Reds starter Nick Lodolo. 

"He was like, ‘Just leave it all out there,'" Williamson said. "That’s all I thought about all night." 

Mission accomplished.