ESSENDON hero Travis Colyer says the explosive burst of speed that led to his match-winning goal against St Kilda was only possible after years of building his fitness.

With the Bombers trailing by five points late in the fourth quarter at Etihad Stadium on Sunday, the Dons speedster received a handball backwards of centre, evaded a tackler and switched on the afterburners as he streaked through the middle of the ground.

Colyer took two bounces running towards goal and drilled a low shot from 50m to wrest back the lead for the Bombers, who then clung on desperately in the final five minutes to win by two points.

The victory improved their win-loss record to 3-2 and Essendon had Colyer's daring run to thank for avoiding a major upset.

"Something I've worked on over pre-season is being able to run out games and using my speed at the end of it," Colyer told SEN on Monday.

"In terms of fitness, it takes a couple of years to get there … but after that I ran straight to the bench and didn't came back onto the ground."

Colyer said the Dons were disappointed with their start to the match, which gave the young Saints "a bit of a sniff".

Essendon was also beaten in contested ball for the fifth-straight game, and the Dons are now -88 on contested ball differential this season.

Colyer said it would be a major focus leading into their clash against Fremantle's big-bodied midfielders – led by Nat Fyfe and David Mundy – at Domain Stadium on Saturday night.

Ross Lyon's undefeated Dockers are +64 on contested ball this season.

"A big focus for us is our contested ball and our pressure, which it was actually all right early yesterday," Colyer said.

"We try and pride ourselves on our pressure, and our contested ball throughout the year has been pretty poor, so they're probably two areas we're really focusing on going into this week against Freo – arguably the best contested ball and pressure side in the competition."