Johnson was called up from Triple-A Pawtucket on Saturday, the Boston Globe's Pete Abraham reports.

Although the Red Sox have yet to announce a corresponding transaction, it's quite possible Clay Buchholz (elbow) will be placed on the disabled list, which would leave an empty spot in the starting rotation. If that's the case, Johnson would likely be one of the leading candidates to fill the spot after the All-Star break, as he owns a 2.73 ERA, 3.23 FIP, 8.5 K/9 and 2.7 BB/9 for Triple-A Pawtucket this season. He's one of the better pitching prospects in the organization, and there's little question the Boston rotation could use some help, even if it turns out that Buchholz is fine.

Johnson's "getting closer" to making his major league debut, according to manager John Farrell, the Boston Globe reports. Farrell was responding to a question about whether Johnson was considered as a replacement for Joe Kelly's spot in the rotation that eventually went to Justin Masterson.

There had been some speculation that Johnson might get promoted to start in place of Kelly -- particularly after another strong outing Wednesday when he allowed one unearned run in 6.2 innings -- but Farrell said if there was any change to be made, Masterson was going to get the first call to replace Kelly. The manager would not commit to Masterson beyond Sunday's start, so Johnson's time could be nigh.

Johnson allowed one unearned run on one hit in 6.2 innings for Triple-A Pawtucket on Wednesday. He walked one and struck out seven with 71 of his 93 pitches going for strikes.

Johnson was in complete command Wednesday, pitching ahead in the count and getting batters out quickly. His name has surfaced within the past few days following Joe Kelly's dismal outing Tuesday. The Red Sox have not confirmed Kelly will be making his next start Sunday and Johnson is a potential fill-in. The left-hander is sporting a 2.57 ERA after Wednesday and is second in the International League with 76 strikeouts in 80.2 innings.

Johnson allowed two runs on three hits and a walk while striking out three in 5.2 innings for Triple-A Pawtucket on Monday. He was making his first start since throwing six perfect innings May 29.

Johnson ceded a two-run homer in the first inning, but settled in after that, retiring 14 of the next 15 batters faced. He was pulled after just 78 pitches, making it two consecutive starts he's been pulled after fewer than 80 pitches thrown. Perhaps the organization is preserving his arm for future use in Boston.

Johnson threw six perfect innings for Triple-A Pawtucket on Friday. He struck out nine while throwing 74 pitches.

Johnson had been scheduled to pitch Saturday, getting an extra day of rest after his pitch count was up the last three starts, but he was needed Friday. As such, he was on a pitch count and was removed from the game despite his perfectness. The left-handed prospect, whose stock has risen considerably the last year, is expected to make his MLB-debut at some point.

The Red Sox are looking for an opportunity to give Johnson his major league debut, the Boston Globe reports.

Manager John Farrell suggested he'd like to get Johnson's initial exposure to the majors out of the way and that there are some spots in the upcoming schedule that lineup nicely for that. The Red Sox are promoting Johnson's pitching mate at Triple-A Pawtucket, Eduardo Rodriguez, to make his initial start Thursday. Both Johnson and Rodriguez are expected to have long-term futures with the organization and the thought is to get them gradually transitioned to the majors.

Johnson allowed one run on five hits while striking out eight in 6.2 innings in a win for Triple-A Pawtucket.

Johnson has righted himself after two-start run in which he displayed an uncharacteristic lack of command (10 walks in 7.2 innings). He did not issue a free pass and reached a three-ball count just once Thursday. It was his best outing of the season.

Johnson threw a complete-game shutout Tuesday for Triple-A Pawtucket.

It was just a seven-inning game as it was front end of a double-header, but still a nice achievement for Johnson, who has been stellar to the start the season. In 16 innings over three starts, he's allowed one earned on 10 hits and four walks while striking out 18. His command of four pitches makes him an attractive candidate for call up at some point this season.

Johnson pitched five shutout innings, giving up four hits and one walk while striking out six for Triple-A Pawtucket on Thursday.

Interesting that Johnson was given the Opening Day start for the PawSox, whose rotation is loaded with top prospects that also includes Henry Owens and Eduardo Rodriguez. Giving Johnson the first start of the regular season is another sign that the organization views him ahead of those aforementioned and more heralded prospects. During spring training, both Owens and Rodriguez were eventually reassigned to minor-league camp while Johnson stayed up with the major league until the very end.

Johnson allowed two runs on six hits and two walks while striking out three in four innings against the Rays on Sunday.

Johnson has allowed eight walks in 15.1 spring innings, but is getting good experience against major-league hitters. He's next scheduled to throw Friday and will begin the 2015 season in the rotation at Triple-A Pawtucket.