The New York Yankees could own a share of the AL's second wild-card spot after Thursday night's action.
The Baltimore Orioles are hoping they will be back in front of New York.
These AL East rivals met for the final time this year to close out a four-game series at Camden Yards, with 13-game loser Phil Hughes making his return to the rotation for the Yankees.
Baltimore (77-68) moved 1 1/2 games ahead of New York with a 4-2 victory in Monday's opener before the Yankees responded with wins by 7-5 and 5-4 the next two nights.
New York (78-68) has pulled within one game of Tampa Bay for the AL's second wild card. Baltimore and Cleveland trail the Rays by 1 1/2 games, with Kansas City two games back.
The season series is tied at nine wins apiece.
"We play this team so evenly, it's unbelievable,'' Yankees manager Joe Girardi said.
This series featured a confrontation between the teams' managers in the opener. Baltimore skipper Buck Showalter is hopeful his team will avoid its first three-game slide since losing four straight Aug. 12-16.
"Tonight was a tough night for us, like last night, but these guys will turn the page and compete their rears off (Thursday)," Showalter said. "Anybody that would want to close the door on us would be making a mistake."
Girardi has opted to turn back to Hughes (4-13, 5.11), who was removed in favor of David Huff for last Saturday's 13-9 loss to Boston. Huff gave up nine runs over 3 1-3 innings.
Hughes is 0-6 with a 5.48 ERA in 10 starts since beating Minnesota on July 2.
"I'm not really worried about redemption or proving anybody wrong or stuff like that," Hughes told the Yankees' official website. "I'm just trying to throw as many quality innings as I can."
The right-hander is 0-1 with a 7.00 ERA in two starts against the Orioles this year, and 2-2 with a 6.16 ERA in his last six outings at Baltimore.
He has limited Chris Davis to four hits in 19 at-bats with one homer, as the majors' home run leader looks to hit his 50th - which would match Brady Anderson's club record in 1996.
Danny Valencia, who has a double in six at-bats against Hughes, went 4 for 4 on Wednesday and has 22 hits in his last 39 at-bats.
The Yankees have outhomered the Orioles 8-1 in this series. Alex Rodriguez and Alfonso Soriano have gone deep twice, with Rodriguez 7 for 15 in his last four games.
The Orioles will start left-hander Wei-Yin Chen (7-7, 3.82), who is 0-1 with a 5.40 ERA in two outings against New York this year and 1-3 with a 5.29 mark in six in his career.
Shortstop Brendan Ryan is hitless in six at-bats off Chen and went 0 for 4 on Wednesday in his Yankees debut after being acquired from Seattle to replace Derek Jeter, out for the season with an injured left ankle.