It also marked a less talked-about mark on history.
The save was the 341st of his career, tying Hall of Famer Rollie Fingers for ninth on the all-time list.
"It's not even another save under my belt, it's another win for the team," Percival said, following the Rays' thrilling 5-4 win.
Wednesday night also marked Percival's 17th save in 19 opportunities -- and his second of the series -- but it was far from a breezy outing.
Chicago's Geovany Soto blasted a homer to left-center field to open the top of the ninth inning and was followed by a walk -- the would-be tying run -- for Mark DeRosa.
But Percival never wavered in his composure on the mound, getting Micah Hoffpauir and Ronny Cedeno to fly out to center fielder B.J. Upton, holding DeRosa at first.
A called third strike to Kosuke Fukudome put the game in the books in front of 31,496 fans at Tropicana Field.
"I don't think he likes the easy save, I think he likes to bring some excitement to the game," catcher Dioner Navarro said, following Tuesday night's equally nerve-wracking save. "And as long as he gets his job done, that's what really matters."
Percival joked that he thought he would use the series to get some work in one-run saves, as both of his appearances vs. the Cubs he allowed the game to get close before prevailing.
"They were two really good, well-played games, and again Percy came through in the end," Rays manager Joe Maddon said.
The outcome is a familiar one for the Rays.
Of Percival's 26 appearances, 17 have been perfect, and 19 have been scoreless.
Next on the all-time save list for Percival is Randy Myers, who has 347. Although Percival says he pays no attention to those individual honors, he did have one prediction for his future.
"I know I'm not getting to 500," the 38-year-old said.
Brittany Ghiroli is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.