Slowey (7-7) struck out five and walked one, and the Twins moved within 1 1/2 games of the first-place White Sox. These teams play six more times this season, all at the Metrodome including three more games this week.
"You have to be strong to play this game, and that's why it's so much more enjoyable that I'm up here now and just getting an opportunity," Span said, adding: "I'm just taking it one day at a time. I don't know what's going to happen. I hope it's not me packing my bags, because I'm having a lot of fun right now."
Losing the spring training competition for the center field job to Carlos Gomez, Span was recalled when right fielder Michael Cuddyer got hurt last month. He has played with such patience, athleticism and determination that manager Ron Gardenhire stuck him in the leadoff spot last week in place of the slumping Gomez.
The team's first-round draft pick in 2002, Span has finally flourished after essentially becoming the forgotten prospect.
"That's exactly what I saw in the couple years I played with him in the minor leagues," Slowey said. "He's not one to get frustrated. He's not one to complain or yell about his situation. He just goes out and gets the job done."
Span is batting .318 with a .405 on-base percentage in 35 games. He and Justin Morneau hit two-run shots in the third inning against Mark Buehrle (8-9), and Brendan Harris later contributed a two-run double.
Buehrle was done after five innings, allowing eight hits and five runs. Only four were earned, thanks to fifth-inning errors by third baseman Josh Fields and second baseman Alexei Ramirez and a questionable safe call by first base umpire Tim Welke that allowed Alexi Casilla to reach on an infield single.
The left-hander was sharp in his first two starts of the second half and brought a 21-11 career record against the Twins into this game, but his night began to go bad when Span whacked his first pitch of the third inning into the facade about 10 feet below the upper deck in left-center field. Morneau followed with his big drive three batters later to make it 4-0.
"I supplied all the power. You throw a fastball down the middle on these guys, and that's what they're supposed to do with it," Buehrle said, later joking that the wind was blowing out in the domed, climate-controlled stadium.
Manager Ozzie Guillen was in good humor, too, when asked about Span.
"I've never seen him before," he said. "I know I've got to check his bat."
Following an excellent five-start stretch during which he went 4-0 with only eight runs allowed in 35 innings, Slowey was hit hard in his previous two appearances -- one before the All-Star break and one after. A finger injury pushed his last one back.
Slowey, strengthening a hold on his spot in the rotation with Francisco Liriano waiting in the minors, never had more than one runner on base in any inning.
In the sixth, after a single by A.J. Pierzynski brought him to the heart of the order, Slowey retired Carlos Quentin on a weak dribbler in front of the plate and struck out Jermaine Dye and Jim Thome. Quentin, Dye and Thome have 71 homers between them.
It just wasn't Chicago's night at all. Center fielder Nick Swisher tried to catch Morneau's homer, but his body was too close on the jump and his glove hit the wall and sailed into the empty football seats.
Dye hit a long, high foul ball to left in the fourth that was initially ruled a home run by third base umpire Bill Welke, then reversed after a conference with his colleagues. Konerko tried to check his swing with one out and Dye on later that inning, but the ball bounced straight to Slowey for an easy double play.
"I just take it one game at a time," Guillen said. "That's why my hair's still black."
Morneau showed off his skill with the glove, too, with three smooth scoops of one-bounce throws to first base. In the third, Alexi Casilla dived to make a one-hop stop of Quentin's smash to second, found the ball after it escaped his glove and bounced off his body, and fired to first for the inning-ending out.
For Slowey, that was the defining sequence that jump-started this potentially defining intradivision series.
"You could just kind of feel the mood in the dugout changing," he said.
Minnesota's Gomez entered the game in the eighth in CF, moving Span to RF. Gomez hadn't played since hurting his back in a collision with the wall in Cleveland while he made a highlight-reel catch. ... Guillen decided against sliding slumping 1B Paul Konerko down from No. 6 in the lineup. He said he wants to show faith in him. "He's not swinging the bat that bad. We've got guys who struggle also," Guillen said. ... Cuddyer took some swings before the game and put a glove on for the first time in a month. That was progress, but Cuddyer will need a brief rehabilitation assignment for his injured hand and still could be out another two weeks. ... White Sox RHP Jose Contreras (elbow) threw a bullpen session before the game, and told Guillen he felt strong. Contreras could be back in early August.