SYDNEY Swans coach John Longmire's future has been locked away, with another long-term contract extension keeping him at the club until the end of the 2020 season.

Longmire's deal was due to expire at the end of next season, but the Swans have moved early to show their support for the coach with a new three-year contract.

After a long apprenticeship under former coach Paul Roos, Longmire took over the senior role for the 2011 season, and guided the Swans to a thrilling 10-point win over Hawthorn to capture the premiership the following season.

The Swans have a history of sustained success under Longmire, having won 16-plus games in each of the last four seasons, and he's never missed the finals in his time at the club.

The new contract will make Longmire the longest-serving coach in the Swans' history, overtaking former mentor Roos, who had 202 games in the role.

"I'm really fortunate to be part of a terrific football club, from the board, to the executive, to the staff and the playing group," Longmire said on Tuesday.

"It's a tough job being a coach but having good people around me at all levels makes it a little bit easier and a lot more enjoyable.

"Strong footy clubs off the field really helps, and stability in the club allows you to focus on the football side, that's critical."

With his future committed to the Swans, Longmire said his goals as a senior coach in the AFL had not changed.

"We've got plenty left to achieve, we're all chasing Hawthorn," he said.

"What they've been able to achieve and the standard they've been able to set over the last few years has been extremely high, so we're all striving to get better.

"The challenge is we know (Hawthorn coach) Alastair (Clarkson) and the Hawthorn football club are doing the same thing so it doesn't get any easier, but we look forward to it.

"It's always an evolving planning system when you're coaching.

"You're looking week to week, but you're also looking a month out (from now), a year out, and years out, at your playing group and what that looks like.

"To maintain your competitive spot on the ladder that you try and achieve every year, you need to be looking at every week in front of you and also beyond."

Longmire's next chance to take on good friend Clarkson and the Hawks comes on Thursday night when the competition's top two teams clash at the SCG, and it's a challenge he's looking forward to.

"There's not a weakness in their side and it's no coincidence they've won the past three flags and they're on top of the ladder by a game, they're a gun team," Longmire said.

"They just love to compete and that's why you love playing them because you know you're going to get tested in that area.

"That's what our blokes know will be in front of them on Thursday night.

"They'll be tested every minute of the game and that's what's exciting about playing them, particularly in front of a huge crowd at the SCG."