Gold Coast defender Rory Thompson is facing fresh injury concerns after injuring his knee in Saturday's matchup with the Bulldogs in Ballarat.

The Suns backman, who made his long-awaited return to football in Round 8 after a four-year stint on the sidelines, was subbed out of the game after sustaining a knee complaint during the second quarter of the Round 10 clash.

Thompson left the field and had his leg assessed by club medical staff before Gold Coast pulled the trigger on their medical substitution.

The Suns confirmed Thompson will undergo scans in the coming days to clarify the full extent of the damage.

Thompson underwent two knee reconstructions in the past four years, with the pair of setbacks keeping the 31-year-old sidelined.

Oleg Markov was brought into the match in Thompson's place as the Suns utilised their medical substitution, however the injuries didn't stop there.

Defender Jy Farrar was later ruled out of the game after failing a concussion test following a head knock in the opening half.

The Suns confirmed after the main break that their half-back flanker would sit out the remainder of the match, with Farrar now set to miss his side's Round 11 clash against Hawthorn at TIO Stadium under the AFL's concussion protocols.