01/27/2013 AT 01:40 PM EST
Will Jennifer Lawrence
walk the red carpet at Sunday night's Screen Actors Guild Awards
The Silver Linings Playbook
star, who's nominated for her leading role playing troubled girl-next-door Tiffany, is currently sick with pneumonia, according to her costar. But sources tell PEOPLE that Lawrence is planning to attend the SAG Awards unless she takes a turn for the worse before showtime.
"She's been very sick," says one source. "She was laying low all week. She plans to be there tonight."
The actress, 22, was unable to attend Saturday's Australian Academy of Cinema and Television Arts International Awards in Los Angeles, where she was honored for her work in the film.
"I'm going to receive this on her behalf," Jacki Weaver told the audience as she accepted Lawrence's best lead actress trophy, according to E! News
. "Poor Jen is really sick. She really is sick. She has pneumonia."
After nabbing a Golden Globe
earlier this month, the actress is a favorite to pick up the SAG Award.
The 19th Annual Screen Actors Guild Awardswill air live on TNT and TBS on Sunday, Jan. 27, at 8 p.m. ET (5 p.m. PT) from the Shrine Auditorium in Los Angeles.