YOUNG Sydney key defender Lewis Melican has been rewarded for a strong season with a new three-year contract extension. 

Melican, who has been a solid contributor for the Swans in 2017 after making his long-awaited debut in round five, will be tied to the club until at least the end of the 2020.

The 20-year-old was rookie-listed by the Swans in 2015 and spent two years plugging away in the NEAFL, but showed outstanding form towards the end of last season, and starred in the club's loss to Greater Western Sydney in the NEAFL Grand Final.

Melican stepped into the senior side to debut against the Giants in round five, in the absence of the injured All Australian Dane Rampe, and the reliability of the old-fashioned backman has kept Aliir Aliir, who had a breakout 2016 season, marooned at reserves level.

Sydney's head of football Tom Harley said Melican's new deal was just reward for plenty of hard work.

"Lewis has been on a gradual improvement curve since arriving at the Swans as a rookie three years ago," Harley said.

"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's fellow Swans youngsters Isaac Heeney, Callum Mills, Will Hayward, Oliver Florent, Jordan Dawson and Darcy Cameron have also signed contract extensions this year.