ESSENDON has stunned Port Adelaide, handing the premiership contenders back-to-back losses for the first time this season in a two point-thriller at Adelaide Oval on Saturday night.

Essendon held the lead at every change and never let the Power hit the front in a tense final quarter to win 8.14 (62) to 7.18 (60).

David Zaharakis was the standout for the Bombers with 30 disposals and seven tackles while David Myers, Jason Winderlich and Zach Merrett were also prominent.

Robbie Gray (30 touches and one goal), Hamish Hartlett and Matt White were amongst the best for the Power.

Essendon coach Mark Thompson said the key to the win was disrupting the Power from their preferred game plan.

"[The focus] was a little bit about contested ball, a little bit about giving Port Adelaide something that made them uncomfortable – they like the fast, flow-on game so we tried to do something about that," Thompson said.

"First half we did it, second half we got a bit scared at the end and nervous and thought we were going to lose it, but we hung on and we're very happy."

Essendon got off to a quick start when Jake Carlisle capitalised on an errant handball from Port defender Tom Jonas just 90 seconds into the first quarter.

Tempers flared shortly afterwards with Gray and Paul Chapman coming to blows in an incident that will draw attention from the Match Review Panel.

The Power finally hit the scoreboard after 19 minutes through Jay Schulz.

The visitors held a six-point lead at the first break though after Joe Daniher and Jackson Merrett combined for a clever goal.

Myers kept the momentum rolling for Essendon in the second stanza after goaling off one step with a powerful kick, but Schulz hit back immediately for the hosts.

Schulz's second goal would be the Power's only major score for the quarter as the Bombers kicked the next three through Brendon Goddard, Patrick Ambrose and Paddy Ryder to push their lead out to 24 points at half-time.

Port started the third term nicely when White dashed inside 50 and unloaded with a goal, but were pegged back after Carlisle booted his second of the game.

The minor scores continued to mount for either side until Gray pounced on a loose ball to goal for the Power to cut the deficit to 16 points at the final change.

It took Port just 44 seconds into the fourth term to signal the start of a comeback when Schulz kicked his third goal.

A captain's goal from Travis Boak had the 46,786 strong-crowd roaring, but Dyson Heppell silenced the home faithful soon after when he intercepted a sloppy kick in Port's defensive 50 and goaled against the run of play.

Kane Mitchell then set up a thrilling final few moments when he scored from inside the goal square after the ball spilled loose from Angus Monfries in what seemed destined to be a decision, or lack thereof, bound to create a maelstrom of controversy over the next few days.

However, the Bombers managed to hold on and keep themselves in what is becoming an intriguing finals equation.

Port coach Ken Hinkley lamented his side's "lack of composure", claiming too many poor decisions were made too often.

"Our lack of composure at times was pretty alarming for us," Hinkley said.

"Games are made up of little moments, little seconds, little minutes and we just didn't work in the right way often enough in that game."