MELBOURNE defender Oscar McDonald has signed a two-year contract, tying him to the club until the end of the 2020 season.

McDonald has played 60 games in the red and blue after debuting in round 22, 2015. 

He has established himself as a reliable key defender, with older brother Tom the other bookend of the team as a forward. 

GET TO THE GAME All your finals ticketing info

"Oscar is a young developing defender who has taken on a lot of responsibility within our defence," Melbourne general manager of football operations Josh Mahoney told melbournefc.com.au. 

"He has built strong understanding with his fellow defenders and we look forward to him continuing to develop in his role." 

The 22-year-old was drafted with pick 53 in 2014 from North Ballarat.

He has played every match this season, taking his current playing streak to 40 consecutive games.