The reigning champions are gearing up for a tough double-header, hosting the unbeaten South East Melbourne Phoenix at RAC Arena on Friday night before travelling to Wollongong to take on the Illawarra Hawks on Sunday.

Perth copped their biggest loss at RAC Arena when they lost to Cairns by 23 points last Friday.

Two days later, Bryce Cotton nailed a game-winning shot in the final seconds to seal a 95-93 road victory over Melbourne United.

Coach Trevor Gleeson was pleased with the response but said his side couldn't afford any more defensive lapses.

"Our defence has been pretty poor to start with," he told reporters on Thursday.

"The last four championships, we've been the best defensive team in the competition and we've let that drag.

"We can't let these guys get off to a great start like Cairns did last week. Our defence is really going to come into whether we win or not."

Gleeson noted that opposition teams had been gambling on smaller line-ups and a faster style of play similar to that of the NBA.

"It seems a lot quicker and a lot more small-ball," Gleeson said.

"They're really stretching the floor and getting to the rack and shooting threes.

"It's a trickle-down from what the NBA are doing. And obviously the skill level has gone up.

"The players in the league are first-class and when you have that on the floor, it's hard to stop."

Gleeson's bid to improve the Wildcats' performance has been complicated by the sudden departure of lead assistant Paul Woolpert.

The club are hopeful of finding a replacement in coming weeks for Woolpert, who has returned home to the United States for family reasons.

South East Melbourne are 3-0 to start their maiden season and Boomers forward Mitch Creek has led the way, averaging 25 points and eight rebounds.

"We'll give him some different looks, small or big," Gleeson said.

"Mitch is borderline NBA. He's crafty and he's getting the team to play so he's a big focus."

Australian Associated Press