"He's been throwing the ball pretty well," said manager Terry Francona. "We like the way he pitches. We think he can handle a start or two or whatever it ends up being."
Pauley, who got the news after Portland's game on Monday, said he felt "pure excitement."
"It's definitely a big surprise," said Pauley. "It's a pretty significant jump."
The native of Colorado said that his parents plan to fly in from Denver to watch his debut.
"I'm sure the adrenaline will be going pretty good," he said. "I'll just have to bear with it and try and keep myself somewhat calm.
"It doesn't really matter where you're at, whether it's Double-A or the big leagues, there's always a little bit of nervousness for every start."
The Sox will wait until after Tuesday's game to put Pauley on the 25-man roster.
"We need to look at Boomer a little bit more and try to get a better read on how close or far away he is," said Francona.
Pauley got the nod over lefty Abe Alvarez for two reasons. First, Boston favored a right-hander against the Blue Jays' power-laden lineup. Second, Alvarez was sent down just over a week ago, meaning that the Sox would have to put someone on the disabled list to bring him back so quickly.
"We didn't want to rush a lefty in to face Toronto, and we didn't think that it would bother [Pauley's] progression," Francona said. "We really enjoyed watching him pitch this spring and getting to know him a little bit. We're excited to watch him pitch and see how he does.
"We have a day off [on Thursday], so it's not like he's got to go eight [innings]. Hopefully, [the Jays'] unfamiliarity with him will get him through."
An eighth-round pick by San Diego in 2001, Pauley was traded to Boston along with Jay Payton in the deal that sent outfielder Dave Roberts to the West Coast.
Primarily a sinkerball pitcher, Pauley also throws a two-seam fastball and curveball. He made three spring starts with the Sox and got a taste of big-league life in an April 1 exhibition outing against Philadelphia at Citizens Bank Park.
"It definitely takes a little bit of the pressure off," Pauley said of his spring experience, "especially getting that start in Philly, too. I kind of know what to expect."
In the zone? When it comes to analyzing Pauley's Double-A ERA and strikeout totals, Francona said that it's important to remember that Minor League umpires have been on strike this season, meaning that amateur umps have been calling the balls and strikes. Based on league-wide numbers, it looks as though pitchers are getting the best of the bargain.
"Trying to translate that plate into a Major League plate isn't easy," Francona said. "I think we have to take that into consideration."
For his part, Pauley isn't worried about adjusting to a more narrow strike zone when he toes the rubber at Rogers Centre on Wednesday.
"I've always been able to throw strikes," he said. "I'm pretty much always around the plate. If I don't get a couple of calls on the corner, I can understand that. I've been there and done that. As long as I keep the ball around the plate and keep the ball down, I think I'll be all right."
Loretta's limp forces lineup change: Mark Loretta was still hobbling around the clubhouse on Tuesday after taking a pitch off his left foot in the eighth inning of Monday's defeat.
"I can't put much weight on it today," said Loretta, who is sporting a nasty bruise on his big toe.
Alex Cora started in Loretta's place, and Francona bumped Coco Crisp up to the leadoff spot.
"When the day started, I was going to have Coco hit seventh tonight, but once I started talking to the trainers and gave Loretta a call, I decided to go ahead and flip-flop him," explained Francona.
"[Loretta] has got all his range of motion, he's just limping around pretty good. I think a day [off] would really help him. He was slowing down as the game progressed. By his last at-bat, he looked like he was moving at about 50 percent."
Loretta is in the middle of a 14-game hitting streak and has 43 hits in May, more than anyone in the Majors. He showed his sore toe to reporters as he awaited a visit from a local podiatrist.
"I expect it just to be today," he said. "The trainers don't think it's anything with the bone. We'll let it calm down today, and hopefully be able to go tomorrow."
So is Crisp in the leadoff spot to stay?
"Who knows?" said Francona. "It could be now, but I'd like him to get just a little bit of time under his belt."
Happy Birthday, Manny: Tuesday is Manny Ramirez's 34th birthday. He shares the birthday with Hall of Famer Amos Rusie, who won 245 games with the New York Giants. Other celebrities born on this date are musician Benny Goodman, football star Gayle Sayers and singer Wynonna Judd.
On deck: The Sox wrap up their trip to Canada on Wednesday, with Pauley squaring off against Toronto lefty Ted Lilly (5-4, 4.00 ERA). Lilly is 5-3 with a 3.57 ERA in 17 career appearances against Boston.