The M4-M5 Link in the WestConnex motorway project could open in 2022.
It was previously expected to be completed in 2023.
Premier Gladys Berejiklian and Minister for WestConnex Stuart Ayres revealed the possibility on Friday while announcing two joint ventures had been shortlisted to build this section of the motorway.
They said the M4-M5 Link mainline tunnel would be a stand-alone project, initially operating independently from the Rozelle Interchange and Iron Cove Link, allowing the link to potentially open early to drivers in 2022.
John Holland CPB Contractors joint venture and Lend Lease Samsung Bouygues joint venture were selected to tender for the project, which will create a non-stop underground western bypass of Sydney CBD.
Work is due to start in 2018.
“This is the most important stage of WestConnex as it will provide the vital connection between the new and upgraded M4 and M5 motorways for tens of thousands of vehicles a day and connect to Port Botany, the Airport and future M6,” Mr Ayres said.
The widened M4 section of WestConnex, between Church Street, Parramatta, and Homebush Bay Drive, is due to open on Saturday July 15.
Motorists will be given a one month reprieve before having to pay a new toll.
Mr Ayres said tunnelling had passed the halfway mark on the M4 East tunnels, which are due to open in 2019.