Since Showalter took over, Orioles starters have gone at least six innings and registered a 1.94 ERA.
"I think it's what people anticipated and hoped for back in March," Guthrie said. "It's taken longer to see what kind of potential we have."
Said Showalter: "If we pitch like this ... we can play with anybody."
The Orioles still own the worst record in the majors (37-74). But they can capture their second straight series, and only the sixth of the season, with a victory Monday night.
"We've got a game tomorrow and we've got to try to walk away with a split and salvage something before we get out of here," said Chicago's Paul Konerko.
The White Sox came to Baltimore having won nine of 11, a surge they expected to build upon at Camden Yards.
"You're playing one of the worst teams in baseball," Buehrle said. "We should come in here and beat these guys."
Buehrle (10-9) gave up four runs and 10 hits in seven innings. He was 7-2 with a 2.70 ERA in his previous 10 starts, and 5-3 with a 2.72 ERA in 14 career games against the Orioles.
"When you look at their lineup, it's like, how is this team that bad?" Buehrle said. "They got (leadoff hitter Brian) Roberts back, and that makes their lineup better. And their pitching staff has done a good job of holding our guys down."
Perhaps it's a coincidence that Baltimore's starters experienced a resurgence when Showalter arrived. Or maybe he was the reason. Either way, Showalter likes what he's seen thus far.
"It's not like these guys have never pitched well this year," he said. "And they seem to be feeding off each other. They want to keep the quality starts going, and I'm OK with that. I really am."
Guthrie was pulled after throwing 116 pitches. Alfredo Simon worked the ninth for his 17th save, despite giving up a two-run homer to Ramon Castro.
Buehrle began the sixth inning by issuing his only walk, to Corey Patterson. Nick Markakis and Ty Wigginton followed with successive RBI doubles to make it 3-1.
Cesar Izturis doubled in the seventh and scored on a single by Roberts.
Izturis earlier got his 1,000th career hit, a bloop to center in the second inning. He has 786 hits in the NL and 215 in the AL, including 178 with Baltimore.
The shortstop also made a sensational diving stop of an eight-inning grounder deep in the hole and threw out Alex Rios at first base.
"Izzy made a great play. That was key," Showalter said.
Rios had two hits and drove in a run for the White Sox, who went 1 for 8 with runners in scoring position.
"It's a combination of good pitching and we're not hitting right now," manager Ozzie Guillen said. "Right now our bats are very silent, but they're pitching well too. Guthrie threw the ball very, very good today."
Chicago second baseman Gordon Beckham left the game with a strained groin. The injury was not serious, but Guillen intends to rest him Monday.
Pie's third homer of the season made it 1-0 in the second, but the Orioles missed a chance to expand the lead when Jake Fox was thrown out by Beckham trying to score on an infield hit by Josh Bell.
Chicago stranded five runners over the first three innings, including four by Carlos Quentin. After being retired in order in the fourth, the White Sox finally broke through in the fifth on a two-out RBI single by Rios.
NOTES: After the game, Baltimore optioned pitcher Troy Patton to Triple-A Norfolk. A corresponding move will be made Monday. ... Chicago catcher A.J. Pierzynski hopes to return Monday after twisting his left ankle Saturday night. He was scheduled to be off Sunday anyway. ... Baltimore is 19-16 in one-run games.