Galloway, a second-half substitute in the 2-2 draw at Suncorp Stadium, rolled his right ankle in stoppage time after a challenge from Roar winger Brad Inman.

The 24-year-old limped off the field, aided by Roar coach Robbie Fowler, and failed to return for the final minutes of the match.

While the ex-Melbourne Victory premiership winner would undergo scans on Sunday to determine the extent of his injury, Mombaerts admitted it didn't look good.

"We have to wait to have the evaluation of his injury but I think it's a big injury," the Frenchman said.

"The referee has to protect the player. He didn't give a yellow card but we see that he tackle the ball but he took the ankle of our player also.

"They (referees) can also make mistakes."

Saturday's draw was highlighted by a thundering second-half strike by Nathaniel Atkinson.

The 20-year-old's first A-League goal came in the 48th minute when he smacked a right-foot finish from outside the box which arrowed into the net.

It was some consolation for Atkinson who was one of four players banned from the Olyroos' Olympic qualifying tournament in Thailand for an off-field incident last year while on national team duty.

Mombaerts praised Atkinson's mental strength, particularly after he'd made an error which led to one of Brisbane's first-half goals.

"That's good with Nathaniel, he had a good reaction, good mentality and he continued to play," Mombaerts said.

"He's young. He has to improve his level but we trust him."

Meanwhile, City have confirmed they have released forward Javier Cabrera effective immediately.

The Uruguayan had played nine A-League games for the club, scoring one goal, and has reportedly agreed to terms with CA Union de Santa Fe in Argentina.

Australian Associated Press