The NL Cy Young winner shut out the Yankees on four hits while striking out two and walking none.
"You're trying to work on things, but you still want to compete so I don't think you ever take a different aggressiveness into a spring training game than you do during the season," Halladay said of the showdown with Posada, which kept the game scoreless.
"You try to get as close to a real situation as you can, so after a few quick innings there, it's kind of nice to try to work out and make pitches when you have to."
The only blemish Halladay had was the black eye he was sporting in his postgame interview.
"Bunting in the cage, three days ago," Halladay said. "It came at my chest and I tried to block it. It was self defense." Yankees starter CC Sabathia held up his half of the premiere spring training pitching matchup. He limited the Phillies to three hits in five shutout innings.
"That's pretty much the CC we're used to seeing," New York manager Joe Girardi said.
Sabathia walked none and struck out two.
"I felt pretty good today, a lot better than the other day," he said. "It was a lot cleaner, and I was actually able to work on some things."
The Phillies put an end to the string of zeros in the sixth after David Robertston relieved Sabathia. Josh Barfield led off with a triple and scored two batters later on a sacrifice fly by Shane Victorino.
John Mayberry Jr. capped a four-run sixth inning with a two-run home run into the Phillies' bullpen. The home run was the third of the season for Mayberry, who is competing for a spot on the 25-man roster.
"I'm just trying to keep focused and do some of the things I intended to do at the outset," Mayberry said.
NOTES: Before the game, 85-year-old Hall of Famer Yogi Berra tripped and fell in the Yankees' clubhouse. He went to the hospital as a precaution and was later released. ... The Phillies gave manager Charlie Manuel a two-year contract extension, taking him through 2013. ... Philadelphia OF Domonic Brown was back in camp two days after having surgery on his right hand. He is expected to miss four to six weeks. ... Philadelphia SS Brian Bocock went back to Philadelphia to have his left wrist examined by Dr. Randall Culp. An X-ray on his hand was negative, but a team official said he might have ligament or tendon damage. ... Yankees closer Mariano Rivera felt fine one day after throwing 35 pitches in his first batting practice session, and didn't rule out making his initial game appearance on Sunday. ... New York DH Jorge Posada started at first base. "Our plans are for him to DH," Girardi said. "It just gives us more options."