Less than a week remains in the regular season and the game of musical chairs is almost complete in each league.

In the American League, three teams are in with the Angels one win away from clinching. In the National League, it's much the same, with the Giants pulling away from the Dodgers for the wild-card spot to round out the field.

That means the matchups for the Division Series are all but set, which leads to some interesting pairings and questions. Some unresolved issues and intriguing aspects with the postseason just around the bend.

1. The Diamondbacks' pitching rotation
In a scheduling quirk, the Diamondbacks and Cardinals, due to meet in the Division Series for the second straight fall, are also meeting this week in an essentially meaningless series. St. Louis has clinched and Arizona has a 4½-game lead over San Francisco; it's unlikely either club can topple Atlanta for the best record (and thus home-field advantage in the NLCS).

But the late-season series means the Diamondbacks will pitch their co-aces, Randy Johnson and Curt Schilling, against the team they'll tackle next week.

If Bob Brenly juggles his rotation -- as he decided to do by bypassing Johnson's start on Tuesday -- to avoid giving the Cards a sneak peak at the two, he disrupts his pitchers' rhythm and risks throwing them off their routines at a critical time. If he pitches them, the Cards may learn something about pitch patterns and gain some extra confidence against them. If Johnson now pitches Thursday, he would be on regular rest to start Game 1 of the playoffs next Tuesday.

But the choice here would seem fairly obvious -- pitch the two and let the Cardinals worry about beating baseball's best 1-2 punch when the games really count in the Division Series.

"I'm not sure it's much of an issue," said one advance scout. "I mean, it's no secret what you're going to see from those two. They've been around a long time. There are no surprises there -- Johnson's got that nasty slider and tough delivery and Schilling is your basic bulldog power pitcher. I don't see how getting an extra look at either one of them a week before is going to change anything."

2. The health of Mariano Rivera
Sidelined for much of the last month with shoulder woes, Rivera pitched a set-up inning in Detroit over the weekend with mostly good results. According to scouts who watched him, the snap wasn't totally back in his pitches, but his velocity was good, considering the layoff, and most telling for the Yankees, he was pain-free.

Questions about Rivera's health and effectiveness are one of two reasons -- the dependability of their starting pitchers being the other -- the Yankees appear more vulnerable than in past Octobers.

One thing's for certain: manager Joe Torre won't be able to use Rivera for more than three outs, as he often has in the postseason. But perhaps that's not such a bad thing. In Rivera's absence, Torre used the trio of Mike Stanton, Steve Karsay and Ramiro Mendoza as a late-inning committee, with terrific results.

All of which gives Torre more options for the playoffs. Stanton, don't forget, has been nearly as efficient as Rivera (albeit in a different role), while Mendoza was the key to the team surviving the 1999 ALCS.

Without Rivera at 100 percent, the Yankees may have lost their air of invincibility, but they may also be deeper in the bullpen than they've been in recent seasons.

3. The dependability of the Twins' rotation
It's a good thing the Twins weren't pushed much in the AL Central race, since their play down the stretch, and their starting pitching in particular, have been real concerns.

Back in the spring, when the prospect of the Twins winning the division seemed more romantic than realistic, their rotation was seen as a team strength. Their front four of Brad Radke, Eric Milton, Rick Reed and Joe Mays had combined for 59 wins in 2001.

But that was before injuries hit and before Kyle Lohse (13 wins) emerged as part of the equation. The other four have combined for just 41 wins (led by Reed's 15).

Radke, back from the DL this month after being sidelined with a nagging groin pull, had pitched well until his last outing when he was lit up. But the real concern is Milton, who suffered a knee injury in August and has struggled mightily in September, with a 14.54 ERA in three outings (he had pitched shutout innings before rain wiped out his last start). Reed suffered a slight hyper-extension of his knee in his last start and was forced to come out. An effective (and healthy) Milton could be critical for the Twins in a first-round matchup with the left-leaning Athletics. The Twins announced Radke and Mays will start the first two games, followed by Reed and Milton.

The importance of home field for the A's
It appears as if the A's will be able to dodge the Yankees in the first round for the first time in three years, which should benefit them since they have the pitching depth to go the distance in the seven-game series.

Entering Monday's play, they held a half-game lead over the Yanks for the best overall record in the AL. But the argument could be made that the A's, should they and the Yanks advance to the ALCS, would be better served by opening the series in New York.

Two of Oakland's Big Three are left-handed -- Barry Zito and Mark Mulder -- and lefties have historically thrived in Yankee Stadium. Indeed, over the last two Octobers, all three starters -- righty Tim Hudson included -- have won Division Series starts in the Bronx.

Then there's this: The A's are 1-4 at home in the last two playoffs against the Yankees.

"It'd be nice the more games you can have at home," said backup Oakland catcher Greg Myers.

But the alternative wouldn't be catastrophic, either.

5. Atlanta's infield
The Braves sport the best winning percentage in the National League, but strangely, have some unsettled aspects to their lineup.

At third base, Vinny Castilla has had a miserable season at the plate even as he continues to contribute with his glove, committing just six errors. It's almost inconceivable that a third baseman could take a .335 slugging percentage into the final week of the season, and yet, that's Castilla's number. He has just 10 homers in 528 at-bats. But the Braves don't have much in the way of alternatives. Marcus Giles has played there some, but Castilla has the clear edge defensively.

Second base isn't much brighter, where Mark DeRosa, Giles and Keith Lockhart have shared playing time. DeRosa's offensive numbers are the best (.308 BA, .352 on-base, .803 OPS), but manager Bobby Cox may opt for the more experienced (and lefy-hitting) Lockhart, particularly against right-handed pitching. Look for a mix-and-match approach, depending on pitching matchups.

Sean McAdam of the Providence Journal covers baseball for ESPN.com.