The state government will invest more than $100 million in savings to fast-track upgrades on Victoria’s busiest freeway which will total to more than $1 billion.

Victorian Premier Daniel Andrews on Sunday said the $400 million first stage of the Monash Freeway upgrade came in $111 million under budget – money which would be used to begin early works on the second-stage upgrade.

The government had previously slated $600 million for stage-two works, which would rise to $711 million with the savings.

The Monash Freeway Credit:Joe Armao

"This is a massive upgrade for one of our most important freeways, it’s all about getting people home faster, getting our freight task to port, to markets quicker and a safer freeway as well," Mr Andrews said.