ESSENDON coach Matthew Knights conceded his side lost its composure, after Port Adelaide came from behind to record an upset three-point win at Etihad Stadium on Saturday.

The Bombers looked to have the game in their keeping, leading for the entire second half until Daniel Motlop's goal at the 22-minute mark of the final quarter.

"I think everyone's hurting post that result," Knights said after the match.

"I thought the effort was sound … the effort was there, but sometimes we've just got to mature as a team when we've got the ball and we've got the game where we want it.

"It's not just one issue - it's just the maturity of the team when we're in those situations to really be ruthless and grind the advantage home."

If one period in particular cost the Dons, it was the third quarter, when they had 12 scoring shots to six but only outscored the Power by 11 points - 7.5 to 6.0.

"Port's finishing was efficient and brutal ... they nailed every opportunity they had," said Knights. "That was the difference in the end.

"[Their third-quarter accuracy] kept them around, and full credit to them, they kept their composure and nailed their opportunities."

The loss is Essendon's fifth in the opening seven rounds of the season, leaving the side wallowing near the foot of the ladder despite an inspirational win last week against bitter rival Hawthorn.

"Bar the Collingwood game (when the Dons were thumped by 65 points on Anzac Day) this team has really endeavoured to be better at our tackling and our pressuring this year, and at the contested ball - and I don't think it's reflected in the win-loss [record]," Knights said.

"If we keep persisting maybe the wins will come our way."