HAWTHORN has been boosted ahead of its do-or-die semi-final clash with Adelaide with the news that midfield pair Isaac Smith and Billy Hartung have signed two-year contract extensions.

Smith, who battled a knee injury in the lead-up to last Friday night's qualifying final loss to West Coast, will now remain a Hawk until at least the end of 2018.

The 26-year-old dual premiership player from NSW extended his current deal, which was due to expire at the end of next year.

"My family have now become attached to the club and my partner's obviously got a lot of friends around here as well. It's a great little community," Smith told the club's website.

"Also success is a big thing as well. We're a successful club and everyone here is doing their bit to make sure that we’re successful and we go out and deliver on the weekends.

"I just love being at Hawthorn."

Smith has played 108 games in five seasons and has averaged over 23 disposals across 22 matches this year.

Meanwhile, Hartung has extended his original two-year draftee contract until the end of 2017.

Nominated for the NAB AFL Rising Star in round seven this year for his 26 disposals against Melbourne, Hartung has played 18 games in his second season. 

He will be one of many players thrilled to see the removal of the substitute vest in 2016, after starting in the green seven times this year.

The 20-year-old travelled to Perth last week as an emergency for the finals side.

"I'm really excited about where the group is going," Hartung said.

"Obviously we've had some good success at Hawthorn the last couple of years and I really want to be a part of that. 

"I've seen the boys last year get the Grand Final success and I just want to be a part of that.

"Hopefully the next couple of years we’re still up there at the very top and I can get a taste of victory myself." 

Smith and Hartung join Ben Stratton, Taylor Duryea, Will Langford and Kurt Heatherley as Hawks to recently re-sign with the club.