Why Longmire chose to bench nine-goal hero Amartey

Joel Amartey of the Swans marks over Crows' Max Michalanney before an early finish at Adelaide Oval.

Sydney coach John Longmire says he was merely protecting Joel Amartey from potential injury when he benched the key forward in the dying minutes of Saturday night's 42-point win over Adelaide.

Amartey had 9.1 to his name and was on the hunt for goal No.10 when he was surprisingly taken off the ground with just under two minutes remaining in the match.

The 24-year-old laughed incredulously when he was taken off, with even his other teammates on the bench surprised to see him there.

It marked the second time in the quarter Amartey had been taken off.

The emerging forward kicked four goals in the second quarter and another four goals in the third to turn the match on its head, and he nailed goal No.9 midway through the last term.

Amartey twice came close to taking a mark inside 50m after that - including one attempt when he nearly collided with a teammate who was coming the other way.

But with the game already wrapped up, Longmire decided to protect his star spearhead from any carnage.

"We want him available," Longmire said, with one eye already on next round's clash with GWS.

"Once we had the game won, it was important for the team that we looked after him and got him to next week."

Amartey's previous best goalkicking haul was four goals, but he blew that to bits with his match-winning display against Adelaide.

Sydney trailed by 23 points late in the second quarter and 16 points late in the third, but Amartey sparked a 10-goal run from the Swans to help the ladder leaders secure the 16.13 (109) to 10.7 (67) win.

It marked Sydney's ninth win on the trot, and lifted them three games clear on top of the ladder.

Amartey was snared with pick No.28 in the 2018 rookie draft, and he's locked in at Sydney until the end of 2026.

Longmire heaped praise on the 41-gamer. "He can launch at the ball, he can be clean, he's good at the ground," he said.

"He's a good athlete. He's added that component this year, he's been able to play out full games and have a real impact.

"He's got a great balance. He knows when to have fun and have a laugh and lighten things up. He's really good at that.

"And then when it comes to the moment to compete, he's been able to cross the line and get into the competitive mode really well and have a big presence in our front half."

Longmire was also glowing in his praise of star ruck recruit Brodie Grundy, who racked up 31 disposals, nine clearances and 49 hitouts in his best performance since joining Sydney at the end of last year.

"He was significant. His contested work in the last couple of weeks have been enormous," Longmire said.

"The longer the games have gone the better he's gone with that. He had a real presence around the footy. His impact around the ball was big."