The change in leadership comes under recently appointed coach John Kosmina, who replaced Rini Coolen at the helm on December 18 for his second stint at Hindmarsh Stadium.

Galekovic, 30, joined the Reds from Melbourne Victory in 2007, and has been an integral part of Adelaide's first team since his arrival - twice named A-League Goalkeeper of the Year.

A statement from Adelaide read: "The move recognised both Galekovic's ability to perform under pressure and his presence within the playing group itself."

"At the same time, the club respects and supports McKain as a player and person in accepting the decision in the best interests of the club."

Defender McKain was named captain in the pre-season after joining from Saudi Arabian outfit Al Nassr.

But Adelaide, who are bottom of the A-League, have struggled and 16-time Socceroo McKain has been unable to find his best form this campaign.

The Reds secured a gutsy 2-2 draw against Sydney in Kosmina's first game back in charge last week, and host Wellington Phoenix on Friday with Galekovic to wear the captain's armband for the first time.