A Sydney teenager remains in a critical condition in Westmead Hospital after he pulled the trigger on a loaded revolver in a suspected game of Russian roulette with friends.

Josh Taylor, 19, continue to fight for his life after being shot in the head on Friday night while sitting in a car outside the Pitt Town IGA supermarket in Sydney’s northwest.

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According to a Fairfax report, the only bullet in the gun discharged and entered his head several centimetres above his ear around 6.30pm.

In November last year, Taylor uploaded a photo of a black handgun to Facebook but it is unclear if this was the same weapon used over the weekend.

On Facebook, his mother wrote of her desperation for her son to make a full recovery.

“Come on son… please please fight like you always have… no words can explain how desperate we are for you to just hang on and fight,” she wrote.

Police continue to investigate the incident and forensically examine the gun.

– with AAP