Patrick Dangerfield has limped from the ground during Geelong's four-point AFL pre-season loss to Essendon in Colac, casting doubt on his availability for round one.
The 2016 Brownlow Medallist pulled up sore at the end of his kicking action late in the first quarter and immediately headed for the Geelong rooms.
Dangerfield played no further part in the game as the Bombers ran out 15.11 (101) to 15.7 (97) winners in front of a 9,115 crowd at Central Reserve.
The injury leaves the Cats facing the prospect of being without Dangerfield and fellow superstar Gary Ablett for their opening-round clash with Melbourne on March 25.
Ablett played no part in either of the Cats' trial matches after suffering a hamstring strain at training last month.
Patrick Dangerfield. Pic: Getty
Dangerfield has only missed one of 49 possible matches during his two years with the Cats.
In another injury blow for Geelong, ruckman Rhys Stanley left the ground early on Sunday with a suspected calf injury.
Essendon also have injury concerns after defender Martin Gleeson was carried off in the fourth quarter in serious discomfort.
In positive news, however, coach John Worsfold said Gleeson only suffered a rolled ankle but will be out for at least a few weeks.
David Zaharakis was also seen limping after the game with his right ankle heavily strapped.
Watch Gleeson's concerning fall:
Aided by a strong breeze, the Bombers kicked four straight goals to open the final term and snatched a match-winning lead through Jake Long in the dying minutes.
Star recruit Jake Stringer impressed for the Bombers with two audacious goals - the first an audacious banana from deep in the pocket, the other an off-balance snap on the run.
Young guns Zach Merrett and Andrew McGrath were typically industrious in the midfield but spearhead Joe Daniher was well held by Geelong veteran Harry Taylor.
Tom Hawkins slotted five goals and was the catalyst for Geelong in a dominant third quarter after trailing by three points at halftime.
Forward partner Daniel Menzel also slotted four majors while skipper Joel Selwood started slowly but finished with 35 disposals, 12 clearances and five inside-50s.