Janssen struck out two during a perfect seventh inning in his spring debut as the Blue Jays beat the Boston Red Sox 1-0 Friday.
"First time out there, I guess it couldn't have gone any better," Janssen said.
Janssen, who finished with 22 saves last season, had surgery in November to address lingering shoulder soreness. After striking out Lyle Overbay and Mauro Gomez, the right-hander got a grounder from Mike Carp.
"His ball was exploding," Toronto manager John Gibbons said. "I thought he was popping the ball pretty good, so that's a great sign."
J.A. Happ continued his strong exhibition season, allowing two hits in six shutout innings for Toronto. The left-hander could begin the season at Triple-A, in a long relief role or at some point move into a starting spot if the Blue Jays decide to drop struggling Ricky Romero from the rotation.
Happ admitted that his undetermined status has weighed on him.
"The great thing is, my teammates are great," Happ said. "That certainly helped."
Happ has given up four runs over 19 innings in six games.
Gibbons again reiterated that Romero is in the rotation.
Romero is 0-1 with a 7.27 ERA in four big league exhibition games. The left-hander had control issues in a minor league game Thursday after working on mechanics with pitching coach Pete Walker.
"He's making some changes, and you don't expect them to happen right away," Gibbons said. "Hopefully his next go around it's going to be better."
Romero is scheduled to pitch Tuesday against Pittsburgh.
Sergio Santos, expected to fill in if Janssen is not ready for opening day, struck out three, walked one and had two wild pitches during a scoreless eighth.
Boston reliever Alfredo Aceves got the start and scattered two hits over five shutout innings.
The Red Sox lineup consisted of mostly backup candidates and prospects. Overbay, the former Toronto first baseman, went 0 for 2.
"We're going to take every day available to us to make a decision on how our bench is going to round out," Boston manager John Farrell said.
Overbay can opt out of his contract Tuesday.
Boston designated hitter David Ortiz (heel) and shortstop Stephen Drew (concussion) remain out, but have been hitting in a cage at the Red Sox complex in Fort Myers. Both could be on the disabled list when the Red Sox open the regular season April 1 at the New York Yankees.
The Yankees will be without first baseman Mark Teixeira (wrist), third baseman Alex Rodriguez (hip) and outfielder Curtis Granderson (forearm). Shortstop Derek Jeter might also miss the opener due to ankle soreness.
"A lot of temporary situations because of injuries," Farrell said. "I'm sure everybody who pays attention to every opening series, you want to see the marquee players perform. In both cases, we're dealing with some banged-up rosters."
Toronto opening day starter R.A. Dickey threw 102 pitches over eight innings in a minor game on Friday.
"It was a great day for me," Dickey said. "Great in the sense that I threw eight innings and felt fantastic. I got better as the game went on, and felt strong in the later innings."
Boston left-hander Jon Lester didn't make the trip and also pitched against minor leaguers.
Toronto infielder Edwin Encarnacion could miss a couple games because of a sore index finger that resulted from an at-bat at the World Baseball Classic.
"It swelled up a little bit," Gibbons said. "The X-ray (Thursday) was fine. No concerns."
NOTES: Toronto claimed RHP Todd Remond off waivers from Baltimore and optioned him to Triple-A Buffalo. The 27-year-old Remond made his major league debut last season with Cincinnati. To make room on the 40-man roster the Blue Jays put RHP Drew Hutchison on the 60-day disabled list. ... Blue Jays 3B Brett Lawrie (strained rib) is increasing his on-field work, but hasn't resumed batting practice. There is a chance he won't be ready for opening day. "If he had to start the season a few days late, so be it," Gibbons said. "We don't want this thing to creep up again." ... Red Sox prospect Jackie Bradley Jr. had one of the two Boston hits. The outfielder is hitting .429 overall. ... Toronto sent RHPs Claudio Vargas and Ramon Ortiz, and INFs Eugenio Velez, Ryan Schimpf, Jim Negrych, Mike McCoy and Luis Jimenez to its minor league camp.