John Longmire is on track to coach the most games in the history of the South Melbourne/Sydney Football Club after signing a three-year contract extension on Tuesday.

Longmire wasn't due to come out of contract until the end of 2017 but the new deal will see him in charge at the Swans until the end of 2020 at least.

The 45-year-old currently sits third on the Swans' all-time games coached list with 138, behind Paul Roos (202) and Rodney Eade (152).

But with another four years in charge after this season, Longmire should comfortably overtake that pair.