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The Bombers led by five goals in the third quarter, but trailed by 11 points early in the final term before Paddy Ryder led a determined comeback to set up the 1.14.12 (105) to 1.14.10 (103) win.
Ryder's fourth goal of the night put the Dons up by eight points late in the term, but Sam Reid's fourth with less than two minutes left on the clock set up a thrilling finale that saw the final siren sound with the ball loose inside Swans' attacking 50.
Star Bombers Jobe Watson, Michael Hurley, Brent Stanton and Dyson Heppell featured for the first time in this year's NAB Cup and all were influential.
Watson was the pick of the bunch with 27 possessions and two goals, while Hurley formed a solid attacking partnership with Stewart Crameri, with the pair booting two goals each.
Rhyce Shaw was outstanding for the Swans with 23 touches, while youngster Luke Parker was lively with 21 disposals and two goals.
The Swans trailed by 13 points late in the opening term, but a late super goal to Adam Goodes set up the four-point margin at the first break.
Jake Melksham replied with a nine-pointer of his own, with the aid of a 50m penalty eight minutes into the second half, but the Swans soon edged in front through goals to Reid and Andrejs Everitt.
The Bombers finished the half full of running, however, and booted the last four goals of the term, including an impressive snap from Watson, to take an 18-point buffer into half-time.
Goodes sent a scare through the Swans camp when he was slung into a point post in a Kyle Hardingham tackle midway through the third quarter. The dual Brownlow medallist lay stunned on the ground, but was soon on his feet and played an integral role in reversing his team's sliding fortunes.
A superb goal by Heath Hocking had put the Dons up by 30 points early in the quarter, but two goals from impressive rookie Harry Cunningham and an opportunistic snap from Goodes helped the Swans slash the Essendon lead to just one point at three-quarter time.
Goals to Reid and Parker put the Swans within striking distance of their third win of the NAB Cup, but they couldn't find a way past a desperate Bombers' defence in the dying minutes.
In further good news for Essendon, Jason Winderlich was subbed into the match in the second half and got through his first game since undergoing a knee reconstruction unscathed.
Courtenay Dempsey continued his own return from a knee reconstruction in stellar fashion with coach James Hird particularly impressed with his form in the first half.
ESSENDON 0.3.4 1.7.7 1.11.9 1.14.12 (105)
SYDNEY SWANS 1.1.3 1.4.7 1.11.8 1.14.10 (103)
SUPER GOALS
Essendon: Melksham
Sydney Swans: Goodes
GOALS
Essendon: Ryder 4, Crameri 2, Hurley 2, Colyer 2, Watson 2, Melksham, Hocking
Sydney Swans: Reid 4, Parker 2, Rohan 2, Cunningham 2, Reid, Everitt, Jetta, Mumford, Goodes
BEST
Essendon: Watson, Ryder, Stanton, Heppell, Crameri, Colyer
Sydney Swans: Shaw, Grundy, Kennedy, Parker, McVeigh, Goodes
INJURIES
Essendon: Nil
Sydney Swans: Jack (shin)
Reports: Nil
Umpires: Leppard, Stevic, Meredith
Estimated crowd: 12,000 at Etihad Stadium
The views in this article are those of the author and not necessarily those of the AFL or its clubs
