Johnson, the 31st overall pick in this year's Draft, was struck in the face by a line drive off the bat of Hudson Valley's Joey Pickard one pitch into the first inning.
"Unfortunately, it hit him flush in the [left] eye socket," Lowell pitching coach Paul Abbott said. "He didn't get a glove on it or anything. It's a scary thing to see.
"We don't know exactly yet how severe [the injury is]. I know he's at a hospital undergoing some tests. They'll check everything with head trauma as well as his cheekbone. It was a flush shot."
After "checking everything," it was determined that Johnson suffered multiple orbital fractures to the left side of his face. Fortunately, there was no sign of a concussion.
Johnson, who received the 2012 John Olerud Award last spring as the best two-way player in the country at Florida, had yet to allow a run over 5 1/3 innings in three games for Lowell.
Still, he already made an indelible impression on the Spinners.
"You're with these kids for a period of time and you get to know them and get to know their character," Abbott said. "He's a great, great kid.
"After it happened, it's a scary thing. He's a tough, tough kid. But he took a heckuva shot."
Time running out: Pawtucket began Saturday's nightcap against Buffalo trailing first-place Scranton/Wilkes-Barre by three games in the International League North Division.
After losing to the Bisons, 2-0, the PawSox are 4-7 in their last 11 games, losing three of those contests by two runs or fewer. If the defending division champions continue playing at this pace they'll be spectators when the Governors' Cup playoffs commence in September.
"Tonight was an example of how we have to pitch better," Pawtucket manager Arnie Beyeler said. "But the guys are working hard and playing hard. We've lost some players, so that's going to give some guys out there an opportunity to step up. We're going to have to get some guys in the middle of the lineup to drive in some runs and pick up for (Mauro) Gomez, (Alex) Hassan and (Ryan) Kalish. Hopefully, some of these guys will be back and swinging the bat sometime soon.
"But it's a team thing. We're just going to keep grinding it out and see where we are on Sept. 1."
Back to the future: Buffalo starter Colin McHugh was superb last year at the Futures at Fenway, albeit with Double-A Binghamton.
McHugh pitched six shutout innings as the B-Mets outlasted the Portland Sea Dogs, 6-4, in 11 innings. On Saturday, he held Pawtucket to five hits over seven scoreless innings.
Local flavor: Fenway Park wasn't exactly foreign territory for three Spinners. Catcher Roberto Reyes is from Lynn, Mass; outfielder/DH Zach Kapstein, the nephew of Red Sox senior advisor Jeremy Kapstein, is from Tiverton, R.I.; and third baseman Matt Gedman, from Framingham, Mass., is the son of former Red Sox catcher Rich Gedman.
Why Fenway is special: Even though Hudson Valley catcher Jake DePew -- who fell a triple shy of the cycle on Saturday -- is no stranger to Major League stadiums, his first visit to Fenway admittedly was something he'll remember for a long time.
"I've played in a few big league parks," DePew said. "I've played in Wrigley Field and Busch Stadium. It was pretty cool playing here today. This is a pretty historic ballpark. It's the first time I've been here, so it's nice to be able come here and play. We enjoyed it. It was a good experience for us."