Lupul missed practice with back spasms and Orr with a leg bone bruise, the team said. Lupul is considered "day-to-day," while the Maple Leafs said Orr will not skate for a week.
Lupul had been taking part in informal skates at the Maple Leafs' practice facility. The 29-year-old left-winger missed all but 16 regular-season games last year because of a broken right arm and a concussion.
Lupul is in the first year of a five-year, US$26.25-million contract signed in January.
Orr played in 44 of the Maple Leafs' 48 games last season and had a league-high 155 penalty minutes.
Prospect defencemen Matt Finn and Kenny Ryan were also not slated to skate. Finn suffered a shoulder injury over the weekend at the rookie tournament the Maple Leafs hosted in London, Ont.