With Yoenis Cespedes playing 3,000 miles east in Boston, Lester handed the ball over to Bob Melvin to the soundtrack of a roaring crowd that granted him a standing ovation. They only got louder when he tipped his cap.
Not an hour later, they were basking in Lester's first victory in an A's uniform, an 8-3 decision over the Royals.
"For me, it aggravates me more when a manager has to come get me, because I feel I didn't get my guys back into the dugout, and that's what we're trying to do, as quickly and as many times as possible," said Lester. "I've never liked that feeling of walking off the mound in the middle of a game. I'd rather shake the manager's hand in the dugout, but that's just me and how I work. But to walk off to the ovation was great. It kind of makes you feel welcome.
"It's pretty cool to be on the other side of it and see these fans go crazy and really love the A's. Hopefully we can continue that and make it worth their while."
"I didn't know if he wanted to come out of that game," said Melvin. "I was kind of scared to go out and take him out of the middle of the inning, but it was time for that, and our crowd was great."
It was the 242nd regular-season start of Lester's career, but first not wearing a Red Sox uniform, and a third of the crowd of nearly 31,000 fans at the Coliseum were also hanging on to giveaway Cespedes T-shirts.
Such is life after Thursday's wildly stunning trade.
"A little bit weird, but this is my new family now," said Lester, "and I'm going to go out and bust my butt and hopefully have more games like today and see where that can take us."
The veteran southpaw wasn't his dominant self, giving up three runs on nine hits -- the first start in which he allowed more than two earned runs since June 7 -- but he was as competitive as he was calm throughout, escaping jams with ease. He walked one and fanned three.
And his new teammates did their part with an eight-run fifth inning.
"That's pretty much what you're going to see from Jon Lester," said Jonny Gomes, who celebrated his return to Oakland with a pair of RBIs. "I think the crowd got right behind him out of the gate, fired him up. The Coliseum was aware Jon Lester was in the house.
"I like our chances with a seven-run lead with him on the hill."
After being unable to put a runner on base through four innings against lefty Jason Vargas, the A's pounced for eight runs on as many hits in the fifth to mercifully put an end to a 20-inning scoreless streak dating back to Wednesday.
Derek Norris' leadoff double gave the A's their first hit, and Gomes, sent back to Oakland in the Lester deal, followed with a popup that was lost in the sun for a base hit. Five of the A's next six batters also singled, as they found their way out of a post-Cespedes-era funk.
Gomes came back to the plate in the same inning and cleared the bases with a single that got past left fielder Alex Gordon, tying the bow on an eight-run inning for an A's team that had scored as many runs total in its previous 31 innings.
Another new but familiar face, Sam Fuld, contributed with a single in the game-changing frame and also helped Lester out with an incredible throw from center field to home plate in the fourth to end the inning.
It was Cespedes-esque, really.
Oakland's departed left fielder collected a hit in his first at-bat in a Red Sox uniform Saturday. Lester, too, was a hit out west.
"We feel really good about our other guys," said Melvin, "but when you can stick in a true No. 1 -- you're talking about three or four guys in the game that pitch No. 1 like he does, that embraces it, wants the pressure, wants to be that guy -- that's awfully nice."
"Guys look up to guys like that, myself included," said Norris. "You want to work harder for him, you want to lay out that extra effort."
He's an Athletic for the remainder of what could turn out to be a special season in Oakland.
"We get so amped up for our first of everything, whether it's your first start, first postseason start, whatever it is," said Lester. "Now it's just getting back to work and the job at hand and getting used to my surroundings. You want to put a good foot forward, so I'm glad today went the way it did, and I'll go back out there in five days and do it again."