Adelaide United coach Carl Veart says his spray at an A-League referee was a culmination of season-long frustration.

Veart faces a fine or possible ban from authorities for his blow-up at referee Daniel Elder after Adelaide's 4-1 loss to Sydney FC last Saturday night.

The Reds coach essentially accused Elder of bias against his side.

"You'd think that in a game of such importance we would have got one of the top referees,'' Veart said post-match.

"But we get a South Australian referee that shows everyone he doesn't want to be South Australian and goes harder against Adelaide United.

"He did it last time when we had him and he did it again."

Veart on Wednesday said his comments "didn't come out the way that I wanted it to come out".

"I wasn't supposed to have a direct go at Daniel," he told reporters.

"I thought he did a good job on the night overall.

"I was just getting frustrated ... over the course of the whole season."

Veart must respond to a please explain from A-League hierarchy by late Monday.

"I still haven't really had time to have a look at it, my focus has been on the game tomorrow night," he said.

"And after that game, then I will have a sit down with the club and we will go through the process."

Adelaide host Western Sydney on Thursday night in their last game before the finals with their play-off ambitions hanging precariously.

The Reds hold fifth spot with 38 points - one point shy of third and fourth place, but just one point ahead of sixth and three clear of seventh.

"Unfortunately we have let some results slip in the last four or five games ... we shouldn't have got ourselves into this position, but we have," Veart said.

"Our team the last couple of weeks hasn't played at a level we want them to play at.

"And now it comes down to the last game of the season where we need to get something ... to go into the finals.

"We don't want to limp over the line and get in to finals and make up numbers, we want to to go in there and be a team that has opportunity to win the grand final - and I believe when we are at our best, we are good enough."