Adelaide United coach Marco Kurz could be forgiven for scratching his head and wondering which Perth Glory side will show up for tonight’s A-League clash at HBF Park.

His opposite number Tony Popovic has made 16 changes in three games as he rotates his line-up in a crowded January schedule.

Popovic doesn’t give much away and has been known to tell a player they are in the squad only when they turn up at the stadium. It will be no different today against top-six hopefuls Adelaide as Glory continue to evolve into true championship contenders.

“That (rotation) is always a reflection of games, of what is coming up and how players have recovered,” Popovic said.

“We treat them as a group but they are individuals and certain players coming off injuries are not at the same level as someone who has played every game.

“Some players look as though they need a bit of a rest.”

The pressing question is whether star midfielder and captain Diego Castro will lead the side for the fourth time or make a fifth appearance from the bench.

Castro has been battling hamstring injuries and when Popovic was asked whether he will take the cautious path for his marquee signing, he said: “I don’t know, your guess is as good as mine. That has not been discussed or decided yet.

“If you look at his game against Melbourne City (last Saturday), I’m sure he could start tomorrow.”

While Kurz will be wondering how to keep Castro quiet wherever he plays, Popovic is making his plans for Spanish defensive midfielder Isaias.

“He’s an outstanding player. He’ll always have his moments in a game. Just like Diego would for us,” Popovic said.

“You can control Diego throughout a match but at some point he will find some space and his quality will shine throughout. It’s the same with Isaias.

“Our job is to keep him very busy defending. If we can play well hopefully there’s more time for him to defend and less time for him to create opportunities for his teammates.”

Glory had a light training session yesterday after the short turnaround from Sunday’s 0-0 draw in Melbourne. It was the first time they had been kept scoreless this season.

“We’ve got another two games to get through before we go back to a game a week. It’s been a difficult period but we’re also enjoying this period,” Popovic said.