JUSTIN Westhoff is unlikely to be a free agent for much longer, with the Port Adelaide utility close to satisfying a games-based trigger to play on at Alberton Oval in 2018.

Westhoff was included on the AFL's official 2017 free agency list when it was released in March given the three-year deal he signed with the Power in March 2014 was due to expire at the end of this season.

However, AFL.com.au understands Westhoff's contract contains a clause guaranteeing him an extension for 2018 provided he meets a set amount of games.    

The 30-year-old has not missed a match since his existing contract began in 2015 – he is on a streak of 88 consecutive games, having last missed a match in round 16, 2013 – and after this year's first 11 rounds is averaging a career-best 19 possessions a game.

It's believed Westhoff is on track to reach the games tally required for a 2018 deal in the next few weeks.

Port also has Jackson Trengove (restricted) and Jasper Pittard on this year's free agency list. The club has held preliminary talks with both players, but is yet to begin contract negotiations with either.

Westhoff, 200cm, remains an important part of Port Adelaide's team with his ability to play at both ends of the ground, as a pinch-hitter in the ruck and even, at times, on the wing.

He also has elite endurance, and Port regularly gives him licence to roam the ground and provide, as required, a target or roadblock.

Westhoff, who turns 31 in October, has averaged 5.7 marks a game this season and is ranked third at Port for marks inside 50 and equal fifth for one-percenters.

The former Central District player has been a remarkably consistent performer for the Power in his 11 seasons at Alberton Oval. From 2010, his lowest placing in the club's best and fairest award is 10th last year, while he finished in the top five from 2011-15, with his best result fourth in 2014.

Selected with pick No.71 in the 2006 NAB AFL Draft, Westhoff has played 213 games and kicked 258 goals.