FORT MYERS, Fla. — Boston Red Sox starter Justin Masterson kept up his strong spring by pitching three perfect innings Tuesday in a 5-1 victory against a split-squad Tampa Bay Rays.

“Able to throw strikes, be in the zone, making progress,” he said.

Masterson struck out four as the Red Sox stretched their Grapefruit League winning streak to five. In five spring innings, Masterson has yet to surrender a run.

Masterson allowed one ball out of the infield. The Rays seemed baffled at times by his sinkers.

“It means they’re not ready yet,” Masterson said. “I’m getting lucky. For me, it’s really about hitting spots and today was pretty good as we kind of moved around, stayed in the middle.”

Masterson was signed as a free agent by the Red Sox in December and figures to be a key part of a rotation also featuring Clay Buchholz, Rick Porcello and Wade Miley.

Manager John Farrell likes what he’s seeing from Masterson not only in two games but in his bullpen throwing sessions.

“I think with each outing Justin is making, we’re seeing more sink to his fastball,” Farrell said. “The ability to make an adjustment more readily from pitch to pitch. And just a pitcher who is becoming more aggressive.”

Pitching well is helping Masterson’s confidence with opening day less than a month away.

“My confidence has been high because everything has been great,” Masterson said.

Masterson looked so strong after three innings it appeared he could have gone for a fourth.

“No thank you,” Masterson said. “Three was enough.”

Masterson, who split last year between Cleveland and St. Louis, is coming off a season in which he spent time on the disabled list with right knee inflammation. He’s also dealt with an oblique issue.

Farrell has observed a healthy Masterson in camp.

“But with each bullpen, each outing that he makes, I think he’s gaining confidence,” Farrell said.

Another plus for Boston was the return of right fielder Shane Victorino after sitting out three games to rest his legs.

YANKEES: Hideki Matsui, a former outfielder for the team, hired as a special adviser to General Manager Brian Cashman,

BLUE JAYS: Pitcher Marcus Stroman will miss the entire season after tearing the anterior cruciate ligament in his left knee during fielding drills.

n Infielder Edwin Encarnacion likely will be out for 4 to 5 days with back inflammation.

INDIANS: Right-hander Gavin Floyd reinjured his pitching right elbow and may need surgery.

PHILLIES: Left-hander Cliff Lee decided after a second opinion from Dr. James Andrews that he will try to pitch through an elbow injury instead of having season-ending surgery.

BRAVES: Left-hander Mike Minor will start the season on the disabled list because of inflammation in his pitching shoulder’s rotator cuff.

METS: Concerned about a drop in velocity, the team scheduled reliever Josh Edgin for an MRI.