CHICAGO -- Glen Perkins is back. How he'll do tonight, in his first big league start since Aug. 2, 2009, is almost impossible to predict.

He went 4-9 with a 6.08 ERA in 23 starts for Class AAA Rochester this season. But those numbers don't tell the story. Perkins spent the season's first three months searching for something. His arm slot was off, probably the result of last year's shoulder injury, and his breaking ball lacked much of its bite.

On June 28, at Scranton-Wilkes Barre, Perkins finally saw the light at the end of the tunnel. . Once again, his line wasn't pretty: 5.1 IP, 5 H, 6 ER, 2 BB, 5 K. Perkins gave up two three-run homers, yet he was still encouraged.

"Other than those I pitched really well," Perkins said. "I remember telling my wife, I hope this is the turning point."

Perkins went on to go 3-1 with a 2.70 ERA in his next seven starts. When Kevin Slowey came down with elbow tendinitis, the Twins summoned Perkins to make this start, against the White Sox, in the biggest series so far this season.

"I'm looking forward to it," Perkins said Tuesday. "It's a big series obviously. I'm just excited to be back here."

Update: Jim Thome is swinging a hot bat, but rather than burn him out playing every night, Manager Ron Gardenhire is sitting him tonight against lefthander John Danks. Jason Repko is getting the start in right field, with Jason Kubel moving to DH.

Lefthanders actually hit Danks much better (.288) than righthanders (.194), but Thome is 1-for-6 for his career off Danks, and again, the Twins have to be sure not to wear the soon-to-be 40-year-old down. Thome will be back in there Thursday, against Gavin Floyd, Gardenhire said.

Kevin Slowey will have a bullpen session Thursday, and the Twins will see how he responds from his right elbow tendinitis before deciding if he can pitch Sunday.

Justin Morneau made it through another workout at Target Field today. That's two in a row.

Update: Andruw Jones was scratched from Chicago's lineup with back soreness. Omar Vizquel enters at third base, with Dayan Viciedo moving to DH and Carlos Quentin moving to RF.

TWINS (64-49)

1. Denard Span, CF
2. Orlando Hudson, 2B
3. Joe Mauer, C
4. Delmon Young, LF
5. Michael Cuddyer, 1B
6. Jason Kubel, DH
7. Danny Valencia, 3B
8. Jason Repko, RF
9. J.J. Hardy, SS

Starting pitcher: LH Glen Perkins (0-0, 0.00 ERA)

WHITE SOX (63-50)

1. Juan Pierre, LF
2. Alexei Ramirez, SS
3. Alex Rios, CF
4. Paul Konerko, 1B
5. Carlos Quentin, RF
6. A.J. Pierzynski, C
7. Dayan Viciedo, DH
8. Omar Vizquel, 3B
9. Gordon Beckham, 2B

Starting pitcher: LH John Danks (11-8, 3.30 ERA)

U.S. Cellular Field. First pitch: 7:10 p.m. TV: FSN. Twins Radio Network