The right-handed reliever was not part of the bullpen in the AL Division Series, but will add long relief depth as the club again goes with 10 pitchers against the White Sox.
Yan went 1-1 with a 4.59 ERA in 49 relief appearances for the Angels during the regular season, but he has not pitched since Oct. 1 in Texas, the second-to-last game of the year.
He said he's kept his arm in shape by maintaining his regular work in the bullpen, but he did not question the decision to keep him out of the first round of the playoffs.
"I fully understand the decision," Yan said. "I understand it and I don't have a problem with it because it was the best thing to do for the team. I knew I had to stay ready. So when they need me to pitch, I'll pitch."
For the second time in the postseason, though, the Angels have decided to go without a left-hander in the bullpen, leaving Jason Christiansen off the roster for the ALCS.
Silver lining: On a day they made the tough decision to leave Colon off the postseason roster, the Angels were able to elevate Jarrod Washburn to active status.
The left-hander was scratched from his start in Yankee Stadium on Sunday because of strep throat and was replaced by right-hander John Lackey, who pitched on short rest. But a course of antibiotics has improved Washburn's condition and he will start Game 2 on Wednesday.
"He is such a competitor that if he can pitch, he will," general manager Bill Stoneman said. "But he's ready to go; he wouldn't start if he wasn't healthy."
Starting Washburn also removes the prospect of starting one of the organization's younger arms, such as rookie Joe Saunders, in a pressure situation. Washburn, who has yet to appear in this playoffs, is 1-3 in seven career appearances in the postseason, making six starts.
Washburn's condition will remain in question, though, and the club will continually monitor his status Wednesday.
"His stamina would be the main thing," manager Mike Scioscia said. "We need to see if he can go out and throw 90 pitches. We need him to get us to the point, like any of the starters, to get us to the bullpen. But we have Esteban Yan and we have Kevin Gregg to give us innings if we need."
Slight breather: Vladimir Guerrero was the Angels designated hitter for Game 1 of the ALCS as the Angels look to rest a few veterans without taking them out of the lineup. Scioscia said he will also look to find a way to give Garret Anderson, Darin Erstad and possibly Bengie Molina some "time off."
"These guys have been grinding," Scioscia said. "This will get Vlad off his feet and reduce the pressure of having to play in the field."
Juan Rivera, who appeared in all five games of the ALDS as the DH, started in right Tuesday and would play left field if and when Anderson is the DH.
"This is what it great about Rivera," hitting coach Mickey Hatcher said. "He can play the outfield when we need him to, and he plays well against lefties and righties. He's been an important piece for us in the postseason because of his power. He brings that dangerousness."
Rivera entered Tuesday hitting .353 with a double and a homer in this postseason.
If it's Tuesday: The Angels played in their third city and third time zone in three days when they opened the ALCS here against the White Sox on Tuesday.
A number of players and people within the organization were obviously tired, but a thrilling win over the Yankees on Monday and a chance to play in the World Series provided plenty of energy.
Still, it didn't prevent a little bit of humor.
"What day is this? What city are we in," Erstad said before batting practice.
There were also some suggestions.
"Maybe we should just have a plane fly us around overhead for a few hours so we can stay on this schedule," Hatcher said.
For others it was all in a day's work.
"I got about six hours sleep," Scioscia said. "For me, it was normal playoffs sleep. You never sleep much longer than that anyway with the game playing in your head."
Mike Scarr is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.