Having three aces is no problem until the Philadelphia Phillies have to pick one to start the first game of the playoffs.

Barring a monumental collapse, the Phillies will win their fourth straight NL East title and secure home-field advantage throughout the postseason early enough for manager Charlie Manuel and pitching coach Rich Dubee to set their rotation for the first round.

Boosted by Roy Halladay, Roy Oswalt and Cole Hamels, the two-time NL champions have a six-game lead over Atlanta with nine games left.

It's been assumed Halladay would take the ball for Game 1. He's 20-10 with a 2.53 ERA, threw a perfect game in May, and is a strong candidate to win the NL Cy Young Award this season.

On nearly every other team, he's the obvious choice.

Not so fast here.

A strong case can be made for Oswalt and Hamels. Both pitchers have been excellent down the stretch while Halladay has faltered by his standards. Both have been dominant in the postseason while Halladay has never thrown a meaningful pitch in October. Both would have far better records if it weren't for lack of run support.

So, who does Manuel consider No. 1?

"Whoever pitches good on that night," he said, avoiding the question. "We have some good pitchers. To say which one is the ace ... I like all three of our top ones."

Halladay has shown signs of wearing down, probably because he's thrown a major league-high 241 2-3 innings. A look at his last six starts compared to Hamels and Oswalt clearly shows he's the third-best pitcher on Philadelphia's staff right now.

Halladay is 4-2 with a 4.32 ERA in that span. The All-Star right-hander has allowed 48 hits, including 10 homers, in 41 2-3 innings. He's given up three runs or more in each of those starts.

Hamels is 5-0 with an 0.82 ERA. The lanky lefty has allowed 27 hits, only one homer, and has 45 strikeouts in 43 2-3 innings.

Oswalt is 4-0 with a 1.25 ERA. The righty has given up 23 hits, including four homers, and has 40 strikeouts in 43 1-3 innings.

OK, now who's the ace?

"It's Charlie," Hamels said. "He gets us motivated. He gets us going."

None of the players or coaches are willing to choose one over the other publicly. Closer Brad Lidge played with Oswalt, Roger Clemens and Andy Pettitte in Houston in 2004-05, and thinks the current trio is better. The Astros lost in the NLCS in '04 and lost in the World Series the following year.

"That was pretty impressive," Lidge said. "But these guys are all in their prime right now, and these guys are amazing to watch."

Halladay desperately wanted a chance to pitch in the postseason after spending 12 seasons in Toronto looking up at Boston and the New York Yankees in the AL East standings. He maneuvered his way to Philadelphia to get this opportunity.

"The postseason is the biggest reason I wanted to play here," Halladay said. "I look at that as the goal. But it's been a lot of fun going game to game. A lot of times the journey is just as much fun as getting there. I'm just trying to keep the day-to-day focus."

Oswalt, who is 13-13 with a 2.80 ERA between the Astros and Phillies, waived his no-trade clause to join Philadelphia on July 29. Though he came close, he didn't win a championship in Houston. Now he's trying to help the Phillies win their second World Series title in three years.

"They've got a ring and I don't," Oswalt said. "Hopefully I can push them to get another one."

Hamels is 12-10 with a 2.93 ERA. He was MVP of the World Series and NLCS in 2008 when Philadelphia captured its second championship in franchise history.

Hamels was the team's No. 1 pitcher that year. He was followed by Brett Myers and Jamie Moyer, who was 45 at the time.

Last year, the Phillies lost to the Yankees in six games in the World Series. Cliff Lee was downright brilliant as the ace, going 4-0 with a 1.56 ERA in five starts. Pedro Martinez was the No. 2 starter and then came Hamels, who struggled all season.

"I think we're in a far better position to go in and carry a team," Hamels said.

Overall, Oswalt is 4-0 with a 3.66 ERA in eight postseason games, including seven starts. Hamels is 5-3 with a 3.86 ERA in 10 games. He was 4-0 with a 1.80 ERA in '08.

The decision on which ace will start Game 1 of the division series could come down to the pitcher the coaching staff feels can best handle going on three days' rest.

That would rule out Hamels because he's never pitched on short rest in his career.

Oswalt is 4-1 with a 2.59 ERA in five career starts on three days' rest. He's even pitched three times on two days' rest, going 2-0 with a 5.21 ERA. Oswalt is at his best late in the season. He's 67-16, counting playoffs, in August-October.

Halladay is 4-2 with a 2.79 ERA in six career starts on three days' rest. He started once on two days' rest and allowed five earned runs in 4 2-3 innings.

No matter who the Phillies send to the mound for the first playoff game — and Halladay is still the likely choice — their formidable rotation makes them tough to beat, and favorites to become the first three-peat NL pennant winner in 66 years.