Montgomery retired the first 18 batters and recorded a career-high 13 strikeouts to win his second straight start and pitch the Blue Rocks to a 3-1 triumph over the Kinston Indians.
Selected 36th overall by the Royals in the 2008 Draft, Montgomery yielded an unearned run on two hits over five innings in his season debut on Thursday. He was even more dominant against the Indians, who entered Tuesday's game with a league-worst .220 batting average.
"It was a good night," Montgomery said. "I really had the changeup working, my curveball seemed to be working well. It wasn't awesome, but I definitely mixed it in there well. It kept them off the fastball."
The 20-year-old left-hander did not allow a baserunner until Jordan Henry reached on an infield hit leading off the seventh inning. Two outs later, Nate Recknagel delivered an RBI double before Montgomery struck out Kyle Bellows, his last batter of the night.
Asked whether he considers himself a strikeout pitcher, the California native said, "Not really. I've never really been one. Actually, I try to get guys out early, make them hit it at people."
The 13 strikeouts eclipsed his previous high of 12, set last Aug. 31, when he limited Myrtle Beach to one hit over 6 2/3 shutout innings.
"This time last year, I was kind of still working on the [curveball] grip. Now I'm really just working on getting that over for strikes, either late in counts or early in counts. It really sets up my other two pitches. I have confidence in the fastball and changeup."
Montgomery breezed through two Class A levels last season, going 2-3 with a 2.17 ERA in 12 starts at Burlington and 4-1 with a 2.25 ERA in nine starts for the Blue Rocks. He has an 0.75 ERA this year in his second stint in the Carolina League.
"I felt a little bit more comfortable [coming back]," he said. "It's still the same game, I'm just trying to work on the things I need to work on to move up -- my curveball and throwing strikes. That's really my main goal, throw a lot of strikes, get ahead of hitters early, get a chance to use the off-speed pitches I've been working on."
With former teammate Danny Duffy deciding last month to take a leave from baseball, Montgomery has emerged as the Royals' top left-handed pitching prospect. Right-hander Aaron Crow, Kansas City's No. 1 pick in last year's Draft, is pitching at Double-A Northwest Arkansas.
"I'm friends with Danny," Montgomery said. "I talked to him. He had to make his own decision and I wish him the best. I'm kind of sad he made that decision; I enjoyed hanging around with him. But I'm just focused on what I do, my pitching and getting better. I don't think that affected me."
Montgomery exited after reaching his pitch count. Eric Basurto retired all six batters he faced, fanning four, for his first save of the season.