SYDNEY defender Nick Smith's future is up in the air after being ruled out for the remainder of the season with a persistent hamstring injury.

The 31-year-old has not played at all in 2019 after undergoing surgery in May.

Smith, who is out of contract at the end of the season, will require another operation in the coming week after first suffering the injury in round 21 last year.

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"Nick's rehabilitation has been interrupted due to ongoing issues with his hamstring," Swans head of football Charlie Gardiner said.

"While the initial signs following surgery in May were positive, Nick has been unable to return to full training.

"After seeking further medical advice over the last few days, it's been decided that the best way forward is for Nick to undergo further surgery.

"It's incredibly disappointing for Nick and for us, as he is a key part of our defensive group and an outstanding on-field leader. He has worked tirelessly in his rehabilitation over the past 10 months and we were hoping to have him back playing in the second half of the season.

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"While he won’t play again this season, Nick remains an important part of the leadership group and will continue to assist in developing our young players."

A decision on Smith's playing future beyond 2019 will be made "in due course", the club said.

Smith has played 211 games for the Swans since his debut in 2008.

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