HOUSTON -- With Houston Astros right-hander Collin McHugh fresh off his final rehab start and back in the home clubhouse at Minute Maid Park, manager A.J. Hinch is set to face some difficult decisions regarding his rotation.

McHugh has missed the entire season with a posterior impingement in his right elbow, but his status with the club is stable. He will return to the rotation this weekend after working six innings for Double-A Corpus Christi on Sunday night, and that could have implications for right-handers Brad Peacock, who excelled in relief earlier this season, and Joe Musgrove.

Peacock gets another chance to start Tuesday night when the Astros continue a three-game series with the Seattle Mariners.

"If it's not (in Baltimore this weekend), then hopefully the next series or sometime on this road trip," McHugh said of when he will make his season debut. "We'll talk between myself and the coaches and the training staff and see what the best fit is that's going to help the team and supplement where we're at.

"We've got a lot of guys who can pitch, and no one wants to give up their spot, especially when they're throwing the ball well. It will be a conversation, but we'll figure it out the next few days."

Peacock is one of those pitchers McHugh is alluding to. He is 7-1 with a 2.63 ERA this season and has excelled as a starting pitcher. In nine starts, he is 5-1 with a 3.18 ERA and has recorded 62 strikeouts in 45 1/3 innings.

Peacock takes a four-game winning streak into his latest outing. Since his only loss, June 9 against the Los Angeles Angels, he is 4-0 with a 1.98 ERA in his past five outings.

Houston has scored 35 runs in Peacock's past two starts, including a 19-1 victory at Toronto on July 9 when the right-hander allowed five hits in six scoreless innings.

He is 4-4 with a 5.48 ERA in 10 career appearances (eight starts) against the Mariners. However, he won twice out of the bullpen against the Mariners in the opening 10 games of this season, allowing one hit and one walk in three scoreless innings.

Seattle will recall rookie right-hander Sam Gaviglio (3-4, 4.31 ERA) from Triple-A Tacoma to start on Tuesday.

Gaviglio made one start for the Rainiers after being optioned on July 7, taking the loss after allowing four runs on three hits and two walks over five innings on July 13 against the Fresno Grizzlies.

Gaviglio is making his second career start against the Astros. He was the losing pitcher on June 24 despite allowing just two runs over six innings in a 5-2 setback.

His catcher might be Mike Zunino, who spent time pregame Monday working on defensive tips with Mariners manager Scott Servais. A catcher in his playing days, Servais appeared in 820 games over 11 seasons with the Astros, Chicago Cubs, San Francisco Giants and Colorado Rockies. The aim of the private session was to reinforce the commitment to defense necessary for Zunino to continue his development as the backstop.

Defensive metrics frame Zunino as having a decent season behind the plate. But given his focus on offense, it is easy to understand why Servais wants to keep Zunino on task relative to his defensive duties.

Zunino hit a two-run double and a solo homer on Monday night as Seattle ran its winning streak to five games thanks to back-to-back solo homers by Kyle Seager and Danny Valencia in the 10th inning of a 9-7 victory.

"It happens to everybody," Servais said. "You've got to get a refresher with where you're at and make a few adjustments.

"Let's not get away from the really important stuff behind the plate. Obviously, the receiving and the metrics, we've spent a lot of time looking at that recently, trying to make a few adjustments there as well."