Perhaps in five months worth of stumbling against some of the American League's worst teams, the Yankees have determined the source of their troubles.

It's something inconsistent, something flimsy and hard to grasp. But there was enough substance there to leave a sizable imprint. The Yankees, through some quirk, have faltered against the Orioles and Devil Rays, and it's cost them any security they might otherwise have earned by this point in the season. Before Monday's win, the Yankees had lost eight of 12 games to the Orioles, who they face again on Tuesday.

"They have given us fits," said Yankees manager Joe Torre. "It's just one of those things. Every year, there's somebody that we're just not comfortable against."

This Orioles club is a bit different than the versions the Yankees have already seen to date, and Monday's Yankees win may in part have been a testament to just that. Baltimore's ace, Erik Bedard, is out for the season with a strained oblique, and rookie sensation Jeremy Guthrie may soon follow suit with the same injury. The Orioles long ago lost closer Chris Ray for the year, and his backup, Danys Baez, is likely finished, too.

That doesn't leave a weak pitching staff with very many options, and so on Tuesday, the Yankees will have an opportunity to feast on an unproven youngster, Jon Leicester. Yet they can't be fooled. Leicester has pitched seven times this season, and four of those outings came against the Red Sox. Against Boston, Leicester holds an 11.88 ERA. Against everyone else, he's thrown a spotless 7 1/3 innings.

The Yankees will have their own intriguing starter in Mike Mussina, who was back to his old tricks last week for the first time since losing his rotation slot to rookie Ian Kennedy. Mussina is now pitching not only to send the Yankees to October, but to earn the right to help them once they get there.

"We're pitching him [on Tuesday] because we like what we saw," Torre said of Mussina. "Obviously, the fact that he's Mike Mussina is important because of the history, but it didn't keep us from taking him out of the rotation, either. We're going to try to win every game we can, and we'll do it by whichever means we can do it."

If the Yankees succeed, they'll make the playoffs for the 13th straight year. It's that simple. The Yankees hold only a relatively slim 3 1/2-game AL Wild Card lead, but it's a lead nonetheless. So it doesn't matter what the Red Sox are doing, or the Tigers or Mariners or anyone else.

It doesn't even matter what the Orioles are doing. When the Yankees are right, all that matters is their own success.

"As a manager, you're watching the scoreboard in April, so no doubt you're watching it in September," Torre said. "But it's nice to know if we do our job on the field, then there's really not much anybody can do about it."

Pitching matchup
NYY: RHP Mike Mussina (9-10, 5.28 ERA)
Mussina was sharp in his first start back in the rotation, blanking the Blue Jays for 5 2/3 innings, despite walking three batters in an outing for the first time since July. Against his original team, the Orioles, Mussina has posted a 9-6 record and 4.51 ERA over the past seven seasons.

BAL: RHP Jon Leicester (2-1, 6.32 ERA)
Leicester shut out the Angels for 5 2/3 innings last Thursday, both the longest and most effective outing of his career. The 28-year-old right-hander has never faced the Yankees.

Player to watch
Shortstop Miguel Tejada owns a .400 average off Mussina in 45 career at-bats and has mashed three doubles and four home runs off the right-hander. Tejada is a career .310 hitter at Yankee Stadium.

Tickets
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On the Internet
 MLB.TV
 Gameday Audio
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•  Official game notes

On television
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On radio
• WCBS, 92.7 WQBU (Español)

Up next
• Wednesday: Orioles (Brian Burres, 6-5, 5.47) at Yankees (Andy Pettitte, 13-8, 3.89), 7:05 p.m. ET
• Thursday: Off-day
• Friday: Blue Jays (Roy Halladay, 15-7, 3.82) at Yankees (Chien-Ming Wang, 18-7, 3.82), 7:05 p.m. ET