Defending A-League Men champions Western United will sweat on scans on Tomoki Imai's shoulder after the crucial defender popped his AC joint in their opening game.
Imai was substituted at halftime in Friday night's 2-1 loss to Melbourne City, with coach John Aloisi expecting the reliable Japanese centre-back to face a stint on the sidelines.
The 31-year-old has barely missed a beat since signing midway through the 2019-20 season and was superb in their run to a maiden championship last season.
"His AC joint, I think, popped out so it doesn't look too good for Tomoki," Aloisi told reporters.
"We just have to wait and see how serious but it wasn't good.
"He wanted to play on but his shoulder was up here," added Aloisi, indicating head height.
"It'll be scans and then we'll have to see and reassess how long.
"We will move on and make sure that whoever comes in will do a good job."
Veteran Nikolai Topor-Stanley was solid as Imai's replacement and Aloisi flagged him as an option going forward.
United became the first reigning champions to lose in the opening round since Melbourne Victory in 2018-19 but Aloisi dismissed any concerns of a championship hangover.
"We lost as well last season in our first game and then we went on a run, so we hope for the same reaction," he said.
"We believe that we'll bounce back because of the way that we performed in pre-season.
"So we know that every game's tough and it wasn't our best performance.
"I wouldn't call it a hangover. It was just that the opposition were better than us tonight.
"They physically were way better than us, I felt. So we'll look at where we can improve."
