TORONTO -- The Astros made a series of roster moves and updated the status of several of their injured players prior to Friday's opener against the Blue Jays at Rogers Centre.
General Manager Jeff Luhnow announced that the team has selected the contract of outfield prospect Teoscar Hernandez from Triple-A Fresno and placed outfielder Preston Tucker on the 15-day disabled list with a strained right shoulder. The Astros also activated right-handed reliever Luke Gregerson from the 15-day DL, while closer Ken Giles was placed on the paternity list and did not make the trip to Toronto.
Rated as the Astros' No. 12 prospect by MLBPipeline.com, the 23-year-old Hernandez joined an already-talented young core, becoming the eighth member of the roster under 25 years old. After a disappointing 2015 campaign, Hernandez hit .307 with 10 home runs, 53 RBIs and 34 stolen bases in 107 games between Double- and Triple-A this season, and he gives the Astros positional flexibility at all three outfield spots. Hernandez made his Major League debut in Friday's 5-3 win over Toronto, going 2-for-4 with a homer as his first MLB hit.

"He's always had a tremendous set of tools," Luhnow said. "He can throw, run and hit for power, but he never really put it together performance-wise here until now. He's really taken his game to another level this year."
Tucker first experienced shoulder pain prior to the All-Star break in Triple-A, but had the injury flare up during Thursday's doubleheader. Tucker has struggled in his second Major League season, hitting just .164 in 48 games.
Gregerson comes off the DL after recovering from a left oblique strain. The 32-year-old threw a successful bullpen session on Wednesday at Target Field and is expected to fit back into a late-inning role. Gregerson is 3-1 with a 3.09 ERA in 44 games this season.

"He brings us stability and allows guys to slot into their normal roles," manager A.J. Hinch said. "Pat Neshek and Will Harris will end up being the sixth and seventh, Gregerson will be usually pitching the eighth inning and Giles pitching the ninth. It makes for a deep back end of the bullpen that can get a lot of outs."
With Giles remaining in Houston with his wife in anticipation of their first child, the Astros are expected to mix and match in any save situations over the weekend.
Worth Noting
• Colby Rasmus had successful surgery on Wednesday to remove a cyst on his right ear. Rasmus was placed on the DL last week and will be shut down for the next 7-10 days. The veteran outfielder has hit .211 with 12 home runs and 48 RBIs.
"We're probably looking at the first half of September or mid-September as a return date," Luhnow said. "This is an unusual situation because we've never dealt with it before, so we're not sure about the time frame to get him back into action."
• Outfielder Jake Marisnick tweaked his right groin in the first game of the Astros' doubleheader against the Twins on Thursday, missing the second game of the twin bill and Houston's series opener against the Blue Jays. Marisnick is considered day to day.