Veteran Edie Falco or Glee's Lea Michele could be big threats for reigning winner Toni Collette and America's comedy queen Tina Fey at this year's Emmy Awards.

The Emmy nominations will be released on Thursday night (10:30pm AEST), with Simon Baker (The Mentalist), Rose Byrne (Damages) and Rachel Griffiths (Brothers and Sisters) anticipated to be part of the list, along with fellow Australian Collette.

The competition for lead actress in a TV comedy series is said to be one of the most interesting categories in the upcoming Emmy's.

Collette (United States of Tara) and Fey (30 Rock) have split the best actress in a TV comedy series at the prestigious ceremonies, with Collette winning the Emmy and Golden Globes and Fey the Screen Actors Guild Award.

Some US TV critics say that it is about time to have changes in the award-giving bodies, with Falco and Michele building up some competition.

Falco, who became popular with her role as a mobster wife in The Sopranos, is the lead cast of dramedy Nurse Jacki, where she portrays a nurse in New York facing conflicts with her high-stress job and high drama personal life.

Glee, a comedy-musical series about a group of youngsters at William McKinley High School in Ohio, is also a favorite of the critics. It has a huge following in the US and draws 13 million American viewers every week.

Magazine Hollywood Reporter bespeaks that Falco will win, taking into consideration her three wins and six nominations for the past year for her role on The Sopranos.

"A former Soprano with multiple wins in a complex, biting role in the lead? It hardly seems a fair fight," The Hollywood Reporter predicts.

Other actresses who could also possibly win one of the six nominations in the lead comedy actress category include Courteney Cox (Cougar Town) and Mary Louise Parker (Weeds).

Baker may also make it to the nominations for his starring role in the TV drama The Mentalist which was nominated in the 2009 Emmy's.

The award was claimed by Bryan Cranston from Breaking Bad. For this year's ceremony, the actor is expected to battle Dexter's Micheal C. Hall.

A nomination for TV drama series may also be snagged by The Mentalist, although Breaking Bad, Mad Men, Dexter and Lost are also strong contenders.

Newcomers Glee and Modern Family may join 30 Rock and Curb Your Enthusiasm for the nominees for comedy TV series.

Byrne could challenge Griffiths for the supporting actress in a drama category. Other possible nominees are Elisabeth Moss (Mad Men), Sandra Oh and Chandra Wilson (Grey's Anatomy), Lisa Edelstein (House), and Ginnifer Goodwin and Chloe Sevigny (Big Love).

The 63nd Primetime Emmy Awards will be held at the Nokia Theatre in Los Angeles on August 29.