ARLINGTON -- Blue Jays left-hander Aaron Loup officially began his rehab assignment with Class A Advanced Dunedin on Saturday, but it's clear he still has to shake off some rust.
Loup retired just one batter and allowed four runs on two hits and two walks. He tossed 13 of his 22 pitches for strikes and was removed with one out in the seventh inning.
The 28-year-old lefty has 30 days to complete his rehab assignment before the club has to either add him to the 25-man roster or option him to the Minor Leagues. But it shouldn't take that long before Loup is ready.
"He's performed all the steps, is doing great, feeling great, we're very optimistic that he's going to do his progression and be fine," Blue Jays head athletic trainer George Poulis said. "That's the nicest thing about a reliever, you don't have to take the time and plan out getting them up to eight, nine innings."
Loup has yet to appear in a game this season after he strained the flexor tendon in his left elbow during Spring Training. He appeared to lose his job when the club signed veteran lefty Franklin Morales to a one-year contract late in camp, but Morales is currently dealing with a shoulder injury and there's no timetable for his return.
That opens the door for Loup to reclaim his spot in the big leagues. He has spent each of the last four seasons in Toronto with a 3.11 ERA over 211 career innings. He's expected to make at least a couple of appearances for Dunedin before moving up another level.

Pentecost back in action
Catching prospect Max Pentecost made his long-awaited return to the Blue Jays' Minor League system this week. Pentecost had not appeared in a game since 2014 after multiple shoulder surgeries derailed his career.
Pentecost returned to action for Class A Lansing on Thursday and has since appeared in two games at designated hitter. Toronto plays on easing him into action at that position until he is ready to resume duties behind the plate.
"We're very optimistic [about the shoulder]," Poulis said. "We just want to get him some activity and it just makes sense to at least get him hitting. His mind gets better and he's in the mix with all the guys down there."
Pentecost is ranked Toronto's No. 7 prospect by MLBPipeline.com. He went 5-for-8 with a home run and two RBIs in his first two games for the Lugnuts.
Worth noting
• Center fielder Kevin Pillar was scratched from Saturday night's lineup because of chest soreness. He was initially listed in the No. 7 spot but was removed approximately 90 minutes before first pitch. Pillar was replaced by reserve outfielder Ezequiel Carrera.
• Right-hander Bo Schultz continued his rehab assignment with Triple-A Buffalo on Saturday night. He appeared in five games for Dunedin and Double-A New Hampshire on his current rehab from offseason hip surgery and allowed five earned runs over 4 1/3 innings.
• Poulis on the status of injured lefty Morales: "Still playing catch, still building up his arm strength, still trying to get where he needs to be as far as feeling strong. But he's going good."