The gym is paying off! Reese Witherspoon shows her toned figure as she dazzles at Devil's Knot premiere in Toronto

Reese Witherspoon's mother must have always told her to stand up straight as a child.

And, no doubt the 37-year-old actress was eternally grateful for the advice on Sunday night.

Perfect posture was all that stood between Reese and an embarrassing wardrobe malfunction at the premiere of her new film at the Toronto International Film Festival.

No slouching: Resse Witherspoon made sure to have good posture to prevent showing too much cleavage at the premiere of her film the Devil's Knot at the Toronto Film Festival on Sunday in Canada

The Walk The Line star was careful not to make any sudden movements as she posed

for photographs at the Devil's Knot screening, with her dress' plunging neckline showing as much cleavage as she could bare.

The actress looked perfectly polished in a black and grey silk chiffon dress that featured a leaf pattern and an unusual neckline, which was a combination of a V-neck with straps that crossed over the star's upper chest.

Flowing down to Reese's knees the dress was cinched in at the waist with a thin black belt.

Say cheese: Reese was joined on the carpet by her co-star Colin Firth

Making the outfit even more eye-catching - as if the plunging neckline was not enough - the 37-year-old added a pop of unexpected colour in the form of green suede pumps.

The star coupled the pointed pumps with a simple black clutch.

Guarding against Toronto's colder weather, before stepping on to the carpet Reese wore a black leather jacket so she could spend time with fans signing autographs without getting cold.

Fin and flirty: The actress looked perfectly polished in a black and grey silk chiffon dress that featured a leaf pattern and an unusual neckline, which was a combination of a V-neck with straps that crossed over the star's upper chest

For her red carpet performance the actress' hair was parted to one side and her blonde locks styled in soft waves.

Joining her on the carpet was her co-star Colin Firth.

Dapper as always the English actor wore a blue suit with a textured black tie and a crisp white shirt.

Sensible addition: Guarding against Toronto's colder weather, before stepping on to the carpet the star wore a black leather jacket so she could spend time with fans signing autographs without getting cold

English gentleman: Dapper as always Colin wore a blue suit with a textured black tie and a crisp white shirt

Unlike Colin, fellow co-star Stephan Moyer skipped wearing a tie all together, preferring instead to wear a simple black suit and an open collared shirt.

Reese had only been in the Canadian city for a few hours before she stepped out on the red carpet.

The 37-year-old jetted in that day wearing a casual but chic look.

Different look: Stephan Moyer skipped wearing a tie all together, preferring instead to wear a simple black suit and an open collared shirt

Colourful co-stars: The film's other stars (L-R) Collette Wolfe and Mireille Enos went for far more bright red carpet looks

Quick trip: Reese had only been in the Canadian city for a few hours before she stepped out on the red carpet

For her flight, Reese wore a pair of washed out black jeans with a simple white T-shirt and a stylish leather paneled cardigan.

Keeping the look relaxed, the star threw her blonde hair back into a bun, donned flats and toted an overstuffed black Celine bag.

The Devil's Knot - based on the book of the same title - is about the real life story of three boys found guilty of a triple murder famously known as the Memphis Three.

Simply chic: For her flight, Reese wore a pair of washed out black jeans with a simple white T-shirt and a stylish leather paneled cardigan

While many thought they were falsely accused the three teenagers - eighteen-year-old Damien Echols, sixteen-year-old Jason Baldwin, and seventeen-year-old Jessie Misskelley Jr. - were only released in 2011.

In the film Reese plays the mother of one of the slain boys, whose own husband later emerged as one of the main suspects in the murder - despite the teenagers already being found guilty.

Colin plays a private investigator who uncovered further evidence exonerating the trio while True Blood's Stephen players John Fogelman, the deputy prosecuting attorney who sort the death penalty.

True story: Devil's Knot follows the story of the Memphis Three and Reese plays the mother of a murdered eight-year-old