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Alfonso Soriano is having one of the best seasons of his career during another lost year for the Chicago Cubs.

Soriano belted a two-run shot for his 30th homer, but Drew Stubbs hit a tiebreaking RBI single in the 11th inning Wednesday night and Cincinnati won 6-5 hours after Reds manager Dusty Baker left the ballpark for chest X-rays.

A team spokesman said the tests were to "rule out pneumonia." Bench coach Chris Speier brought the lineup card to home plate and there was no sign of the 63-year-old Baker during the game.

"I guess the good thing is it's not pneumonia, but the bad thing he has an irregular heartbeat," Reds head trainer Paul Lessard said. "They will keep him at the hospital and run some more tests in the morning before he is set free."

Baker, who managed the Cubs for four seasons, hopes to rejoin the Reds on Friday.

Brandon Phillips' lazy popup with two out in the 11th on a windy night at Wrigley Field was misplayed by Cubs right fielder David DeJesus, allowing him to reach second. Stubbs then smoked a run-scoring single to left against Alberto Cabrera (0-1).

Logan Ondrusek (5-2) worked out of a bases-loaded jam in the 10th to earn the win. Jonathan Broxton earned his fourth save in six chances since joining Cincinnati in July.

Soriano connected in the sixth for Chicago, which trailed 5-1 after five innings.

The 36-year-old Soriano now has six 30-homer seasons, including two with the Cubs. He has 103 RBIs, one short of matching his career high.

"I'm very proud of myself, working hard," he said. "If I'm feeling healthy, my numbers are there."

Soriano didn't hit his first home run of the year until May 15, but still managed his first season with at least 30 homers and 100 RBIs since 2005.

He continues to earn praise from manager Dale Sveum for the example he sets for a young, rebuilding team.

"The people in that clubhouse know how important he is to everybody," Sveum said. "To play with injuries and to play every day, things like that are invaluable in that clubhouse."

Joey Votto reached four times and drove in three runs for the Reds (90-59), who have won three straight to become the second team in the majors to reach 90 wins. Cincinnati also moved a season-high 31 games over .500.

Cincinnati lowered its magic number to clinch a playoff spot to one with the Los Angeles Dodgers splitting a doubleheader at Washington. The Reds' magic number for a second NL Central title in three years is three.

The Reds used five straight singles to score three times in the third. Votto drove in a pair with a bases-loaded single to left and Ryan Ludwick singled in Stubbs to make it 4-0.

Votto also doubled in a run in the first.

Reds starter Mike Leake retired his first 11 batters before Anthony Rizzo's two-out single in the fourth. After a walk to Soriano, Starlin Castro singled in Rizzo.

Castro finished with four singles and leads all major league shortstops with 76 RBIs.

After Soriano's homer in the sixth, Castro singled and scored on Luis Valbuena's double down the left-field line, trimming the Reds' lead to 5-4. Leake then caught a lackadaisical Valbuena wandering off of second base to end the inning.

"I don't know what he did," an irritated Sveum said. "Obviously he went to sleep."

The 24-year-old Leake allowed four runs and six hits over six innings.

The pesky Cubs rallied with two outs in the eighth against J.J. Hoover, who walked three batters — including one that forced in the tying run.

Cubs starter Chris Rusin was tagged for five runs and 10 hits in five innings. The 25-year-old had given up just three runs and nine hits over his last two starts — both of which also lasted five innings.

NOTES: Ludwick was taken out for precautionary reasons in the fifth inning due to left groin tightness. ... Reds LHP Aroldis Chapman said his fatigued left shoulder "feels good" after throwing a bullpen session. Chapman said through an interpreter that he likely needs two or three more bullpens to work on his command. ... The Cubs agreed to a new player development contract with nearby Class-A Kane County. The contract runs through 2014. ... Chicago sends Jason Berken (0-1, 7.20 ERA) to the hill in the series finale Thursday against Johnny Cueto (17-9, 2.92).