CHICAGO -- There was a moment in the ninth inning of the White Sox 6-4 walk-off victory over the defending World Series champs from Boston on Thursday night at Guaranteed Rate Field where Nicky Delmonico didn’t know if he would have a chance to be a hero.

On the first pitch from Ryan Brasier, with runners on first and third and one out, Delmonico hit a foul popup that looked playable for first baseman Mitch Moreland.

“I was watching it the whole way,” said Delmonico with a broad smile. “I was watching Moreland, back and forth. I took a deep breath after it went foul.”

After that deep breath, Delmonico connected off of a Brasier slider for the second game-ending blast of his career. The ball had an exit velocity of 98.8 mph and traveled 380 feet per Statcast, as Delmonico was sitting offspeed.

“We have a pretty good scouting report on those guys that late in the game,” Delmonico said. “They all throw hard, but early on they’re going to come at you with offspeed. So I went up there looking for an offspeed pitch up I could handle.”

“[Trying to get] a swing and miss down under the bat,” said Brasier of the walk-off homer. “Made a bad pitch, and he did what he’s supposed to do.”

This winning rally began with third baseman Rafael Devers’ error on a routine José Rondón grounder, and Rondon moved to third on Yonder Alonso's single to left. All of this uproar began after the White Sox had struck out in five straight at-bats against the Red Sox bullpen.

But for a team working under the mantra of “Ricky’s boys don’t quit,” maybe the winning rally actually was being set up all game. Lucas Giolito returned from the injured list for the White Sox after being out of action since April 18 with a left hamstring strain, and while he did not factor in the decision, he still looked impressive.

Giolito yielded three runs on seven hits over five innings, striking out seven and walking two. He topped out at 95.9 mph with his fastball and recorded 16 swinging strikes among his 98 pitches.

“Being on the injured list, not fun. Never want to go back, knock on wood,” Giolito said. “Felt good. Great. No, like, soreness or pain or any of that with my hamstring.”

“He was really good after a 10-day hiatus,” White Sox manager Rick Renteria said.

The White Sox had a chance for a big inning against Boston starter David Price in the sixth, when Jose Abreu walked, and James McCann doubled to right-center with one out. Abreu was sent home on the double by third-base coach Nick Capra, but Abreu was nailed on a throw from center fielder Jackie Bradley Jr. to shortstop Xander Bogaerts to catcher Christian Vazquez. Yoán Moncada and Rondon followed with singles to tie the game at 3.

On the flip side, five White Sox pitchers held the Red Sox hitless in nine at-bats with runners in scoring position leading to 10 stranded runners. It all led up to Delmonico, who not only had to pause momentarily for the foul ball, but also on the home run, to make sure Bradley -- who also made an attempt at McCann's two-run homer in the first inning -- couldn’t make the play.

It was the team’s third walk-off victory of the season, second walk-off homer and second straight walk-off win, with Alonso delivering the two-run single in Game 2 of Wednesday’s doubleheader against the Orioles.

“These guys are awesome,” Delmonico said. “I love coming to the field and playing with these guys. We don’t give up.”

“We've been expecting this,” Giolito said. “We know the talent's always been there, especially some of these guys, the starts they've gotten off to. It's just a matter of us kind of putting every piece of the game together and producing good games, good solid, clean baseball.”