According to shortstop Jimmy Rollins, Oswalt jokingly answered the question after Halladay threw a no-hitter against the Reds in Game 1 of the National League Division Series.
"Roy made a joke, saying, 'We better go out and get 25 hits when he pitches,'" Rollins said. "He's looking for about eight or nine runs. You all better get me a whole bunch of runs, basically."
Oswalt hopes to help the Phillies take a 2-0 series lead when he faces the Reds in Game 2 of the NLDS at Citizens Bank Park on Friday at 6 p.m. ET on TBS.
Phillies manager Charlie Manuel has already put Halladay's no-hitter behind him and is looking for Oswalt to have a quality start.
"Last night is gone," the skipper said. "That performance will always linger maybe in your mind and everything like that, but that's one game. We've got two more games to win to actually to win the series.
"That gives us great confidence. We're up 1-0. And, you know, like that's kind of how I want Roy Oswalt to feel. I just want him to do the same thing that Roy Halladay did. Just go out there and be comfortable, get a comfortable atmosphere and pitch to his ability and his knowledge on how to pitch. Just be himself."
Oswalt was himself when watching Halladay's no-hitter. Oswalt said he had a feeling by the sixth inning that something special was going to happen.
"I think I'm more worn out than [Halladay]," Oswalt said. "I was rooting him on pretty hard. He had unbelievable stuff as far as location, and I was trying to pick up some things that he was doing to the hitters. He had the stuff to go all the way."
It was the second no-hitter Oswalt has witnessed in person. The first one came on June 11, 2003, when six Astros threw a combined no-hitter against the Yankees at the Old Yankee Stadium. Oswalt started that game for Houston, pitched one inning and left because of the groin injury.
To Oswalt, there is no comparison on which no-hitter was better to watch.
"We had a no-hitter in New York, but it was six guys," Oswalt said. "To get six guys on the same day and have great stuff is hard to do. But as far as seeing a game live, [Halladay's no-hitter] is the best I've ever seen."
The odds of beating Cincinnati appear to be in Oswalt's favor. In his career, Oswalt is 23-3 with a 2.81 ERA in 34 games (32 starts). However, he doesn't expect to throw a no-hitter like Halladay.
"I don't expect to do the same thing," Oswalt said with a chuckle. "I'm going out there looking for a quality start, pretty much."
With the Astros, Oswalt was often asked about his dominance over the Reds until he finally picked up a loss. The question made a comeback recently.
Oswalt was quick to point out that the Reds are a different team than the one he faced when he was with the Astros.
"The team changes so much," Oswalt said. "There's really no way to explain it from when I first started. There's not a guy left on that team, I don't guess, that played then. So it changes so much.
"I don't know if it's just the way it lined up. A few times, I actually gave up a few runs against them and my team came back and scored me a few. So we just kind of lined up where I pitched on the days that we scored some runs and some days I was able to shut them out. Really wasn't one direct thing, I don't guess."
Bill Ladson is a reporter for MLB.com and writes an MLBlog,