The Blue Jays hope it's the start of something big.
The 26-year-old Perez, who has made 29 appearances out of the bullpen this season, is set to make his first Major League start when he takes the hill against Guillermo Moscoso and the A's in the series finale.
"[Perez] has got an ability to funnel and channel those emotions and that adrenaline into the strike zone," Blue Jays manager John Farrell said. "His composure since the first time he pitched for us has been very good. It has been outstanding. It has really allowed him to settle into a role of responsibility out of the bullpen, to the point of providing the opportunity for him to start."
Perez has confidence and experience as a starter. He went 2-2 with a 4.60 ERA in eight starts at the Triple-A level this season.
"I feel prepared because when I was in the Minor Leagues, even though it's a little bit different, I faced the lineup two or three times," Perez said. "I'm going to use all of my pitches -- fastball, changeup, slider -- and I can throw all those pitches at any time. Depending on who's hitting and how they're taking my approach, that's how I'm going to attack, but I'm always going to stay with this approach of pitching."
Moscoco he has picked up three wins in his past four starts, the most recent coming Tuesday against the Orioles. In that start, he allowed just two earned runs on five hits while fanning four over six innings.
"The last four or five outings, we've been doing a really good job," Moscoso said. "I've been making quality pitches, going deeper in the games. That's all I'm looking for."
Both pitchers expect a challenge.
"I've been doing a good job coming out of the bullpen and throwing in the Minor Leagues, but I was always prepared in the back of my mind," Perez said. "Always felt like the chance might come one day, so I was prepared for that."
Blue Jays: Bautista's status in doubt
Jose Bautista was a last-minute scratch for Saturday's game against the A's because of tightness in his neck, and it's unknown if he will play in Sunday's finale.
The slugger suffered through similar symptoms with his neck earlier this season. He was removed from a game against the Yankees on May 1 and missed five games.
Edwin Encarnacion went 1-for-4 on Saturday and has reached base safely in 18 of his past 19 games. He's hitting .344 during that stretch.
A's: Willingham gets a breather
Josh Willingham was given Saturday off -- until he delivered a pinch-hit home run in the eighth inning -- but should return to the lineup Sunday. He leads the team with 22 jacks.
Oakland's defense continues to be a work in progress. The club has committed 12 errors in its past 11 games and has 102 errors for the season.
The A's have won four of their past five games and are 18-16 since the All-Star break.
The A's are 5-4 against the Blue Jays this season. Toronto has still won 12 of the past 21 meetings, dating back to 2009.