Orioles 4, White Sox 3 (10): Matt Wieters delivered a two-out, two-run single in the bottom of the 10th to give host Baltimore the walk-off victory.
The Orioles were 1-for-17 with runners in scoring position before Wieters singled off closer Addison Reed (5-3) to plate Nick Markakis and pinch runner Chris Dickerson to pull Baltimore within 1 1/2 games of Tampa Bay for the second wild card in the American League.
Conor Gillaspie had put Chicago ahead with a pinch-hit homer off Tommy Hunter (4-3) in the top of the 10th but Reed couldn't hold the lead and suffered his sixth blown save to send the White Sox to their ninth consecutive defeat.
Brian Roberts homered and Chris Davis had an RBI double for the Orioles, who got two scoreless innings from Darren O'Day and a perfect ninth from closer Jim Johnson.
Dayan Viciedo homered and doubled while Paul Konerko had two hits and an RBI single for the White Sox. Chicago's Hector Santiago lasted five innings, giving up two runs on seven hits while Orioles left-hander Wei-Yin Chen struck out eight and allowed two runs on six hits over six innings.
GAME NOTEBOOK: Orioles DH Danny Valencia went 3-for-4 for his eighth multiple-hit game in his last nine and is batting .563 (18-for-32) in that span. ... Viciedo ended an 11-game homerless drought and notched his first game with at least two extra-base hits since July 29. ... Davis' run-scoring double gave him 39 two-baggers on the season and, coupled with his 48 homers, put him closer to becoming the third player in history (Babe Ruth, 1921; Albert Belle, 1995) with 50 homers and 40 doubles in a season.