After allowing 17 runs over his last two starts with Boston before being placed on the 15-day disabled list with a right elbow strain, the pitcher was thrilled with the way his arm felt.
"Cortisone is a beautiful thing," said Lackey, who will be activated Sunday to start against Oakland. "My elbow felt a lot better than it has been feeling, that's for sure. I felt like I was letting it go pretty free and easy. That's something that I haven't been able to do this season."
Asked if he was just about pain-free after getting some rest the last three weeks, Lackey smiled and said, "That's not ever going to happen."
The 32-year-old was making his first start in the International League, after coming up through the Minors in the Angels' organization.
Lackey needed 19 pitches to get through the first inning, but he settled in after that, allowing one run on three hits while walking none and striking out four.
Lackey was able to throw all his pitches with good command, spending most of the game ahead in the count.
Pawtucket manager Arnie Beyeler said he's used to seeing big league players throw a lot of strikes at that level.
"Guys that have stuff do," he said after the PawSox's 5-4 victory in 11 innings. "That's part of the deal. You can't pound the zone if you don't have stuff to get guys out with, and he's got three, four pretty good pitches, and that's why he does what he does."
"That's part of being a big league guy, coming down here," said Lackey, who reached as high as 93 mph with his fastball. "Young guys kind of like to hack on you."
Older guys have been hacking on Lackey this season as well, as the right-hander left the big league club with an 8.01 ERA.
Norfolk's Matt Angle, who had hit two career home runs in 500 Triple-A at-bats leading into Tuesday's game, used the "young-guy approach" to drill a first-pitch fastball off Lackey into the outfield stands.
But Lackey remained encouraged with the way his body felt as he pitched into sixth inning after throwing a side session just three days ago.
"Honestly, as soon as I stepped out there, I felt like my arm was feeling good," said Lackey, who treated the start like a regular-season game, mixing in plenty of breaking pitches. "But I definitely still had to dial in some location."
Darnell McDonald was also rehabbing in Pawtucket on Tuesday, as he hit third and played center field. McDonald went 0-for-3 with an RBI and was hit by a pitch.
McDonald has been nursing a strain left quadriceps muscle and was placed on the DL on Thursday, making him eligible to be activated on June 10.
But he has just 21 at-bats this season, and Beyeler said it looked like the outfielder's timing was off.
"I don't expect him to be sharp, that's why he's down here," the skipper said. "That's a tough thing for those guys. They go up to the big leagues and guys go up there and play that type of role, those pinch-hit type guys. You have to be a special guy to be a bench-guy up there."
Josh Reddick is 5-for-9 in three appearances with the Red Sox while taking McDonald's spot, and Ryan Kalish could be ready to start taking at-bats as Pawtucket's designated hitter in the coming weeks, providing a log-jam in the outfield and difficult decisions to be made.
Jason Mastrodonato is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.