Only just back in the national team fold after a long lay-off due to a knee reconstruction, which ruled him out of the World Cup, Kruse sent shudders through the Australian camp when he went down clutching his knee during the session on Tuesday.
The 25-year-old appeared to slip and fall awkwardly as he was about to receive a pass from Australia team-mate Tommy Oar.
After staying down for several minutes, Kruse eventually got to his feet and left the session immediately, although Australia's medical staff are confident the injury has nothing to do with his recent ACL problem.
It is still unclear if the problem will rule Kruse out of the Belgium fixture and then Saudi Arabia in London four days later.
Prior to the recent scare, Kruse spoke with Football Federation Australia about his excitement to be back in the national fold and just how tough the last year has been since sustaining the injury in training with Bundesliga outfit Bayer Leverkusen.
"The initials stages I was just trying to get over the pain of the knee. Trying to get walking and sleeping was difficult," Kruse said.
"As it got closer to the World Cup it really sunk I particularly you see the boys on social media or the internet and it was quite difficult to take.
"They did a fantastic job at the World Cup and it kind of brought the passion back to the public. They can see the football we were trying to play and the young players and everyone stood up
"It was a little bit bittersweet not to be involved but I'm proud of the team, now hopefully I can help the team and play my part leading into the Asian Cup."
Kruse has yet to return to competitive action with Leverkusen as he fights to win his place back in the side.
He contemplated a loan move to try and get some regular match time before deciding to stay at the German giants and fight for his spot.
