Former Sydney co-captain Jarrad McVeigh is in doubt to face St Kilda next Saturday after playing through a tight hamstring in the 42-point win against North Melbourne on Sunday at Etihad Stadium.
McVeigh, 32, played in attack and kicked two goals in the second quarter despite looking hampered.
He looked in trouble when Ed Vickers-Willis easily chased him down on the lead in the second term but the premiership Swan used his guile to push the Roo away at the right moment before turning around, executing a clean one-handed pick-up and booting the goal to extend the margin to 19.
The dual club champion played just under 55 minutes of game time and finished the match on the bench with his right hamstring iced.
"His hamstring did tighten up. He's mentally strong. There's not many that can keep playing with a tight hamstring," Longmire said after the game.
"(He) was pretty important for us."
McVeigh has had his struggles with soft tissue ailments in recent times. The clash against the Roos was just his second game for the season after struggling with a calf issue.
The coach said McVeigh was needed on the field to ensure his side could keep rotating players.
"It was important for us, particularly when it happens so early, to keep him playing if he thought he could," Longmire said.
"He's a very good judge of what he can and can't do and he used his smarts really well."
Oliver Florent was rested after having played five games in his debut campaign and Longmire said there were no doubts about the first-round selection's fitness for next week.
The Swans have a six-day break before returning to Etihad to face the Saints.
It looms as a crunch clash if Sydney, with two wins and six losses, is to keep its finals aspirations alive.
Longmire was confident his side has improved after a slow start.
"We've been better the last two weeks. We've just got to keep building on that," Longmire said.
Skipper Josh Kennedy was outstanding from the outset and he finished with 37 disposals, 17 contested possessions, nine clearances and a goal.
"He was so happy about last week, getting the first win (against the Brisbane Lions), and really set himself to play well. He's mentally strong and was fantastic, particularly early," Longmire said.