DENVER -- The Orioles started September with a flurry of roster moves as they hit the heart of the playoff race.

The Orioles recalled third baseman Coby Mayo (the club's No. 1 prospect and MLB Pipeline's No. 9 overall), as expected. They also brought up catcher David Ba?uelos, who had one Major League at-bat earlier this season; put third baseman Ram¨®n Ur¨ªas on the injured list; activated Zach Eflin off the injured list; and designated for assignment outfielder Forrest Wall.

• Seven injured O's who could impact stretch run

MLB active rosters expanded from 26 players to 28 on Sunday.

Mayo started at third base and collected his second MLB hit during Baltimore's 6-1 victory over the Rockies in the series finale at Coors Field.

Mayo had a tough first stint in the big leagues last month, going 1-for-17 (.059). The 22-year-old got his first hit in his final game, knocking a single against the Nationals on Aug. 14.

He spent his subsequent time with Triple-A Norfolk ¡°simplifying things¡± on the offensive side, as he put it.

¡°Trying to go back to what I was doing early in the year -- good launch angles, hitting the ball hard, not trying to do too much -- because I know I'm a good hitter,¡± Mayo said.

Mayo appreciated the chance to get his confidence back at Triple-A and noted how different things seem on his second stint in the Majors.

¡°You're comfortable down there a little bit,¡± Mayo said. ¡°So you go down there, and you play with less pressure on yourself. I went down there and didn't put a lot of pressure on myself and played and did my routines. And when I got here last night, I didn't feel like it was the first time. I felt like I've been here before, and I'm ready.¡±

With Ur¨ªas on the injured list with a right ankle sprain, Mayo is likely to get another chance to establish himself at third base.

¡°He's been working really hard behind the scenes at third base, so I'm excited to see him come back,¡± first-base coach Anthony Sanders said. ¡°I think going down gives him a little breather and then come back now and, hopefully, hit the ground running.¡±

In addition to his 65 games at third base for Norfolk, Mayo also played 23 games at first base, developing his versatility as a corner infielder.

¡°I put a lot of work in throughout the year,¡± Mayo said of his increasing confidence at first base. ¡°There's some points where I played a lot and some points where I haven't played as much, but I'm ready for if they need to play first.¡±

Ur¨ªas had been leading the offense over the past two weeks, hitting .341 with two doubles, a triple and four home runs, and 15 RBIs over his past 15 games. He was hit by a baseball that skimmed his nose in the fifth inning Saturday and then sprained his right ankle defensively at third base and left the ballpark on crutches.

¡°Kind of disappointing night,¡± Sanders said of the injuries to Ur¨ªas and starting pitcher Dean Kremer, who suffered a right forearm contusion when he was hit by a line drive. ¡°Worried about Dean and Ur¨ªas. ¡­ Just kind of cross our fingers and just hope that we can just stay healthy down the stretch.¡±