By Callum Twomey

Gold Coast SUNS chairman John Witheriff has dismissed claims the club's board is disappointed with coach Guy McKenna's tactics during the team's loss to Greater Western Sydney on Saturday.

McKenna withdrew senior players Michael Rischitelli, Matthew Warnock, Jarrod Harbrow and Sam Iles at half-time with his team leading by five points, replacing them with youngsters Piers Flanagan, Tom Hickey, Alik Magin and Jacob Gillbee.

The Giants went on to record their first victory against an AFL club by 13 points.

There had been speculation the club's board was unhappy with McKenna's moves, but Witheriff said the reports had no merit.

"No, it doesn't (have any substance)," Witheriff told radio station 3AW on Tuesday.

"We have gone to a lot of trouble in setting up a structure where the board has a particular role, the CEO has a role and the coach is answerable to the CEO and our structures, but any calls about on-field strategy lie in the hands of our coach.

"It's just not the role of the board to stick its nose into coaching matters - full-stop, end of story."

Witheriff said the loss to the Giants was not alarming, but that the GC SUNS were into their second phase as a club and that winning games would start to become more important.

He said phase one started four years ago as the Suns set-up the foundations of the club, building an administration and fan base, and Metricon Stadium.

Phase two, he said, was about success.

"The reality for us is we're moving into phase two and phase two means in the next four years we've got to win," Witheriff said.

"I'm not worried about whether we succeed this week or whether our performance gets a little bit up and down, but there are some pretty firm performance criteria on everyone in our club, including me as chairman, and people are measured against that."