Sergio van Dijk had equalised with a stunning goal with just under a quarter of an hour to go, before the Reds pushed for a winner at Hindmarsh Stadium, allowing Perth's Michael Baird to score a late brace down the other end to clinch the match.

"We lost the game, of course it's not good but we are in the pre-season now, there are a lot of things that are more important," Coolen said after the match.

"In the first-half I don't think we played well, we made a lot of mistakes but the second-half was much better.

"There were two or three possibilities to win the game so that was okay and I was happy with that part of the game.

"But the last five or 10 minutes we made a few mistakes, we wanted to score that goal (the winner) and we took risks, and we had to be focused for the counter attack and we didn't do that, which cost us."

Despite the defeat, Coolen still felt there was reason for optimism from the Reds who were without several regulars including Travis Dodd, Eugene Galekovic and Mathew Leckie.

He added: "The score was 3-1 but there are still good things to talk about.

"I let the players play for as long as possible, because we need to prepare for the first game (of the season), so you're not happy when you lose your first game, but that wasn't the most important thing and I saw a lot of things that we can discuss."

The Reds face North Queensland Fury in their final pre-season match next Friday night and Coolen said it'll be an opportunity to keep developing the side.

"The mistakes we were making in the first-half were just easy balls and we have to work on that," he said.