Bassitt threw seven sharp innings against his first major league team and Matt Olson homered, leading the Oakland Athletics to a 2-0 victory over Lucas Giolito and the Chicago White Sox.
The 30-year-old Bassitt was drafted by Chicago in 2011 and made his debut with the White Sox in 2014 before he was traded to Oakland in the Jeff Samardzija deal.
"Every time I pitch against these guys for my career, I'm going to try to prove to them they made a mistake," Bassitt said. "That's the reality of it. Anyone that says different is lying. So yeah, any time I pitch against these guys, they're going to get my A' game."
Bassitt (8-5) permitted four hits, struck out seven and walked two. Olson, Robbie Grossman and Chad Pinder had two hits apiece for the Athletics, who are fighting for position in the AL wild-card race.
Manager Bob Melvin said Bassitt's fastball was the best it's been this season.
"That saved me today because I had nothing else besides the fastball," Bassitt said. "You have your best pitch and it's the best of the year, it's going to play out well for you."
Giolito (12-6) struck out a career-high 13 in six innings. The All-Star right-hander allowed two runs and five hits.
The White Sox had won five of seven.
Olson connected for his 23rd homer after Matt Chapman just missed his own drive in the fourth. Right fielder Jon Jay leaped to try to catch Chapman's deep fly ball at the fence, but it bounced out of his glove for a double.
Olson was batting 6 for 30 this month.
"I went out there in the fourth inning and didn't have my focus like I had the other innings," Giolito said. "You do that in the big leagues, they're gonna hurt you."
Giolito struck out the side in the third and sixth innings and ended his outing with five straight strikeouts. He has just one victory in his last seven starts after winning eight straight outings in May and June.
"Coming out of the break, I was a little flat. I'll admit that," Giolito said. "I think my legs weren't under me, but the last two turns I really got in the weight room and made the routine better. Doing things more for maintenance. It's a long year."
Bassitt is 3-1 with a 2.00 ERA in his last six starts.
Liam Hendriks struck out two in the ninth for his 12th save in 17 opportunities.
The A's went 3-3 during their week in Chicago, dropping two of three against the Cubs before splitting their first two on the South Side. Oakland won the season series against the White Sox 5-1.
Former White Sox outfielder and designated hitter Harold Baines, who was inducted into the Baseball Hall of Fame on July 21, was recognized during a pregame ceremony. Former teammates Ron Kittle and Ozzie Guillen and Hall of Famers Jim Thome, Carlton Fisk, Tim Raines and Tony La Russa were in attendance.
"I'm very grateful, very honored, but it really hasn't hit me yet," Baines said about his induction.
The A's struck out 16 times.
"It's a lot better feeling when you strike out that many times when you win the game than if you lose it," Melvin said. "At least we didn't have to run down the line too hard today and nobody got hurt pulling any hamstrings."
Athletics: OF Stephen Piscotty (illness) was out of the starting lineup.
White Sox: OF Leury Garcia was scratched from the starting lineup. Manager Rick Renteria said Garcia wasn't feeling well. ... RHP Kelvin Herrera (strained right oblique) was reinstated from the 10-day injured list. He is 3-3 with a 7.36 ERA in 38 relief appearances.
Athletics: LHP Brett Anderson (10-7, 3.99 ERA) is scheduled to start a two-game series Tuesday at San Francisco opposite LHP Madison Bumgarner (7-7, 3.74 ERA).
White Sox: RHP Dylan Cease (2-4, 6.00 ERA) will start the opener of a three-game home series Monday against Houston. RHP Zack Greinke is expected to start for the Astros.
More AP MLB: https://apnews.com/MLB and https://twitter.com/AP-Sports
Olson pulls homer to right field
Matt Olson pulls the ball to deep right field as the Athletics go up 2-0 over the White Sox.