The Eagles were able to stick with the undefeated St Kilda most of the day and led by seven points late in the third quarter, but gave up the first five goals of the final term to fall to 4-11 for the season.
Cox returned for his first game in three weeks to take on former teammate Michael Gardiner, but his day ended early with a recurrence of a groin injury, and the Eagles will now reassess what to do with his recovery.
"His groin got sore, and we limited his ruck work and game time in that second half,” Worsfold said of Cox.
“It got sore so quickly, which was disappointing. We'll have to work out what the best program is for him.
"I'm not sure what it will mean - that's a medical decision really. We were obviously hopeful he wouldn’t get sore during the game, but he did by half time. You would expect that he will struggle to play next week."
Quinten Lynch played well with Cox off the ground and finished with 24 possessions, nine marks and 24 hit outs, but Worsfold will need to get the stop-gap ruckman some help from either Nic Naitanui or Mark Seaby in the coming weeks.
Seaby was again good in the WAFL for West Perth on Saturday with 17 possessions, 34 hit outs and three goals, including a massive pack mark and goal to secure a draw for his team.
"We won't go to Nic to be the No. 1 ruckman and carry the big workload, so we will certainly have a look at ‘Seabs’ if Dean is not right to go," he said.
"I didn’t see ‘Seabs’ play, but I've heard the reports, and his form has been very good all year."
Despite finding positives from the performance, Worsfold was still disappointed to lose after his side took it right to the ladder-leaders for the first three quarters only to wilt early in the last term.
"It's another loss, so that's disappointing,” he said.
“But we worked pretty hard, saw some really good things and some things we still need to work on. I'm pleased with the way the guys are attacking what we are asking them to do and taking the game on.
“There were some great chances for us to attack, but we made poor decisions that put ourselves out of the game."
Worsfold was also pleased with how Eric MacKenzie and Darren Glass kept Justin Koschitzke and Nick Riewoldt to a single goal between them.
"I don’t know what ‘Kosi’ did really, and that's a good thing because we weren’t worrying or making a change," he said.
"Eric started on Riewoldt and looked out of sorts there, but fought back, and I can't remember Koschitzke doing a lot of damage to us. Glassy's job on Riewoldt was outstanding."
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