Gumbleton was subbed out in the first term on Wednesday night at Etihad Stadium with what appeared to be a hamstring injury.
The Dockers recovered from a poor second term to beat the improving Bulldogs 0.15.7 (97) to 0.9.15 (69) in front of only 4914 fans.
Gumbleton, the former No.2 draft pick, was traded from Essendon last year after requesting a move back to his home state.
The key forward has played only 35 games since his 2007 debut because of a shocking run of injuries.
It was a much-improved performance from Fremantle after they opened the pre-season with an 84-point loss to West Coast.
After trailing by 14 points at halftime, they kicked goals to two in the second half, including an unanswered run of seven.
Ruckman Aaron Sandilands dominated for Fremantle and Michael Walters kicked four goals.
Bulldogs midfielders Koby Stevens and Jack Macrae impressed, while Brownlow Medallist Adam Cooney starred in the first half.
The Dockers kicked the first two goals of the game and led by that margin at quarter-time.
But the Bulldogs dominated the second term, opening up Fremantle at times and matching them for defensive intensity.
The 'Dogs kicked five goals to one in the quarter.
When star recruit Stewart Crameri kicked his first goal at four minutes into the third term, the Bulldogs led by 22 points.
But a strong contested mark and goal from captain Matthew Pavlich at 13 minutes signalled a comeback from last year's grand finalists.
They kicked the last four goals of the term to lead by a point at the last change.
Crameri had a bad miss late in the term when he lined up directly in front on a set shot.
It proved costly, with the Dockers quickly moving the ball down the other end.
Sandilands marked and goaled to put Fremantle in front for the first time in more than a quarter.
Dockers coach Ross Lyon confirmed Gumbleton had suffered a hamstring injury.
But their medical staff are hopeful it is a standard three-week layoff and nothing more serious.
"It's really disappointing for him, he'll be really flat because we know his history of back-hamstring stuff," Lyon said.
"He hadn't missed a session and if anything, we'd lightened off (with him) a little bit this week.
"I feel for him, because he's worked his hardest and shown strong character.
"He needs to be resilient from here and keep going, not drop his bundle."
Lyon said their second quarter was really disappointing, but overall saw some pleasing signs in the win.
He praised Sandilands, saying the giant ruckman led the way in the second quarter when they were struggling.
"But it's a sharp reminder we still have plenty to do in a short period of time," Lyon said of the match.
Bulldogs coach Brendan McCartney said the Dockers made his team pay for scoring turnarounds, where the 'Dogs kicked a behind and Fremantle rapidly went down the other end for a goal.
"They are a hardened strong team and we have got a way to go in that, but we gave up some simple goals," McCartney said.
"There was a lot to like, but we would have liked to finish closer or in front."
Bulldogs forwards Shaun Higgins and Tom Williams made successful returns from long-term injuries.
FREMANTLE 0.4.4 0.5.4 0.9.5 0.15.7 (97)
WESTERN BULLDOGS 0.2.3 0.7.6 0.8.10 0.9.15 (69)
Nine pointers: Fremantle - Nil. Western Bulldogs -Nil.
Goals: Fremantle - Walters 4; Ballantyne, Pavlich, Mzungu 2; Sandilands, Mayne, Mundy, Barlow, Suban. Western Bulldogs - Giansiracusa 2; Cooney, Wood, Stevens, Dahlhaus, Hunter, Honeychurch, Crameri.
Best: Fremantle - Sandilands, Walters, Mundy, Barlow, Mzungu, Duffield. Western Bulldogs - MacRae, Stevens, Cooney, Wallis.
Umpires: Ray Chamberlain, Brett Ritchie, David Harris.
Official Crowd: 4914 at Etihad Stadium.