Then came the final pitch of the at-bat, a low breaking ball that Lackey was asked about after the game -- specifically, if he had broken out a rare splitter to retire one of the games most feared hitters.
"Nah, I don't have one of those," said Lackey, who gave up three runs (two earned) over five innings on Saturday. "I wish."
Lackey used the pitch, described simply as a breaking ball, to finish off Harper for the second time, atoning for a mistake he made to the slugger in the first.
Harper got the best of Lackey in their first meeting, smashing a fastball over the middle of the plate off the video board in right and putting the Nationals ahead, 1-0. But Lackey looked solid the rest of the way, working in and out of trouble against one of the best lineups in the Majors.
"He's a bulldog out there. He's going to give you everything he's got," said catcher Alex Avila, who was paired up with Lackey for the first time. "Today was like an American League game, to be honest with you. That lineup is more like an American League lineup -- at least that's what it felt like for me, trying to navigate through that order."
The relentless lineup would cause some problems for Lackey, dinging him for a pair of runs in the fourth.
Lackey allowed two straight singles to start the frame before surrendering the first run on an Anthony Rendon sac fly to left. Willson Contreras, who got the start in left field, attempted to throw home on the play, but his throw actually bounced off the runner at home, and Daniel Murphy was able to advance from first to second before eventually scoring on a two-out single.
Lackey kept his composure, though, striking out Edwin Jackson to end the frame and returning for the fifth. The veteran right-hander faced the top of the order once more, but he got through it, striking out Harper for out No. 2 and getting Ryan Zimmerman to fly out to end the inning.
"Johnny Lackey battled, battled, battled," Cubs manager Joe Maddon said after the game. "He gets the win, right? Johnny gets the win."
Scott Chasen is a reporter for MLB.com based in Chicago.