Haeger will be making his first appearance with the Dodgers. Billingsley will be returning from a strained left hamstring that caused him to miss his scheduled start on Wednesday in San Francisco.
Torre said Haeger's selection comes with "an asterisk" and could change if he's needed to pitch long relief on Saturday night, because Jeff Weaver is still unavailable after starting for Billingsley on Wednesday. Torre said he expects Weaver back in the bullpen by Sunday.
Billingsley tested his hamstring again on Saturday with a bullpen session at game speed. His normal turn in the rotation would be Monday, but he will get an extra day after throwing 30 pitches on Saturday.
"Everything felt fine," he said. "I threw a lot more pitches, just to try to get more comfortable out there and get my rhythm back because I haven't pitched in a while. I'm happy with it."
Billingsley said he's likely to do some fielding drills Sunday or Monday to be comfortable fielding his position. He injured his hamstring coming out of the batter's box a week ago Friday.
Haeger, 25, was promoted from Triple-A Albuquerque on Tuesday and has not pitched. He went 11-6 with a 3.55 ERA and four complete games for the Isotopes. While known for throwing the knuckleball, Haeger has a more varied repertoire than traditional knuckleball specialists like Hoyt Wilhelm, Phil Niekro and Tim Wakefield, Torre said.
Brad Ausmus said he has an oversized catcher's mitt from catching knuckleballer Steve Sparks with Detroit in 2000. Not knowing that, Diamondbacks broadcaster and former Dodgers knuckleballer Tom Candiotti brought to the dugout an oversized mitt that Mike Piazza used to catch Candiotti with the Dodgers and offered it to Ausmus and Russell Martin if needed.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.