Lewis Melican during the round 16 AFL match between the Sydney Swans and the Gold Coast Suns at Sydney Cricket Ground on July 8, 2017 in Sydney, Australia.

Young Sydney defender Lewis Melican has signed a new three-year contract extension that will see him remain at the Swans until at least the end of the 2020 season.

The 20-year-old made his debut for Sydney in round five against the Giants earlier this season, and has since played 10 games for the Swans, and booted his first goal in his career against Gold Coast last weekend.

Sydney's head of football Tom Harley told the Swans' website the club is thrilled to secure Melican's future.

"Lewis has been on a gradual improvement curve since arriving at the Swans as a rookie three years ago,” Harley told sydneyswans.com.au.

“After overcoming a few injuries, he was able to put together a really solid pre-season and force his way into the senior team.

“His poise with the ball, competitive nature and overall character hold him in good stead and we are very happy that he has committed to us for the next three seasons."

Melican has averaged 12.4 disposals, 3.8 marks and 3.0 rebound 50s per game so far this season.