A 24-year-old left-hander selected in the fourth round of the 2014 amateur draft, Montgomery had a 3.20 ERA in two starts and four relief appearances during spring training, striking out 17 and walking three in 19 2/3 innings.
Montgomery beat out more established pitchers in a group that included Luis Cessa, Chad Green and Bryan Mitchell.
''He just kind of pitched himself into it,'' said Yankees manager Joe Girardi, who announced the decision Monday after New York beat the Rays 8-1 in its home opener. ''He has four-pitch mix. He had a very good downhill angle. He's 6-6. He's left-handed. He was able to use his breaking ball extremely well, whether it was his curveball or his cutter. His changeup's good. And when he locates his fastball, it's really good.''
Luis Severino had been scheduled to start Wednesday but will now start Thursday's series finale. Girardi said he made the decision to push back his other starters after Masahiro Tanaka threw 92 pitches over five innings Saturday at Baltimore, the second straight lackluster outing for the Yankees' ace.
Montgomery made his first start of the season last Thursday, allowing an unearned run and three hits in five innings for Class A Tampa.
New York opened a spot on its 25-man active roster by optioning Chasen Shreve to Triple-A Scranton/Wilkes-Barre after the left-hander pitched the final inning Monday.
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