Boucher was Philadelphia's postseason starter until he sprained a ligament in his left knee in Game 5 of the Eastern Conference semifinals.
Leighton took over and had three shutouts in the East finals to lead the Flyers to their first Stanley Cup finals in 13 years.
Boucher was expected to miss the rest of the postseason. Boucher said after Wednesday's practice there were no setbacks in his rehabilitation. He wants to be in uniform for Saturday's Game 1 against the Chicago Blackhawks.
Boucher is 6-4 in the playoffs this year with a 2.33 goals-against average.