Newcastle Jets' marquee player Emile Heskey is in doubt for the club's A-League opener against Sydney FC on October 11 after suffering a knee injury on Wednesday.
The former England international striker was assisted from the field at AAMI Park after a tackle from Melbourne Victory's Nick Ansell during the first half of their trial game played behind closed doors, which the Jets won 1-0.
"It looks like a sprained medial ligament to his left knee," a Jets' spokesman said.
"He's going to have scans tomorrow. The early diagnosis is three to four weeks.
"He would be very much touch-and-go (for Newcastle's first A-League game). Potentially, he could miss that one (against Sydney FC)."
Former Liverpool star Heskey, 35, scored nine goals last summer in his first season with the Jets.
Nathan Burns will also have scans after feeling hamstring tightness in the warm-up, the club spokesman said.
James Virgili scored a second-half penalty for the Jets.