MEDICAL staff have confirmed injury plagued Adelaide United left-back Cassio ruptured a tendon in his hamstring during the Reds' loss to Melbourne Victory at Etihad Stadium on Saturday.
The club was reluctant to place a time frame on the Brazilian's injury but he will be almost certainly be forced off the pitch until after Christmas, and the injury could sideline him for much of January and February.
He will have a better idea of the extent of the injury after he consults a specialist later this week.
Cassio, who had scans on the injury on Monday night, limped from the pitch just 12 minutes into the Victory match and had to be subbed off for Steven Lustica.
The latest injury setback casts doubt over the 33-year-old's future at Hindmarsh.
A torn hip tendon and a quad injury have sidelined the club's longest-serving player since July.
Meanwhile, Sydney FC say they are ready for the sternest defensive test yet of their A-League season - Newcastle strike duo Adam Taggart and Emile Heskey.
Jets coach Gary van Egmond has indicated his is ready to unleash the in-form Taggart and the now-fit Heskey up front together on the Sky Blues in Saturday's round eight encounter at Allianz Stadium.
Taggart, who has scored six goals in three weeks to race to the top of the A-League goalscorers' list, and former England striker Heskey are set to spearhead the Jets attack for the first time this season in a match between two of the competition's in-form teams.
Both the Jets and Sydney FC are enjoying three-match winning streaks, with Newcastle's only defeat this season coming at the hands of the Sky Blues in round one.
They conceded the most goals of any side last season and those wounds were opened again this season in a 4-0 round two loss to Brisbane Roar and a 2-0 loss to Western Sydney Wanderers a week later.
Since then Sydney have found some early momentum but without suspended defenders Tiago Calvano and Pedj Bojic the mission to stop Taggart and Heskey has become that much harder.
But defender Matt Jurman, who is beginning to make his mark at the Sky Blues after returning from Brisbane Roar this season, believes the hosts are up to the challenge.
"I watched Newcastle last week and Taggart played well in getting that hat-trick ... it is going to be a good test for us on the weekend and all the boys are up for it," Jurman said at training on Tuesday.
"Taggart and Heskey are two good players but at the end of the day it is up to us to stop them.
"Not that long ago both teams were down the bottom of the ladder and under a bit of pressure, now we have both moved up but we need to keep our momentum going."