"Steve is known around the world for playing the game in the right way," Nicholson said.
"It is wrong to query his integrity or that of the Australian team.
"Steve has responded very clearly to questions regarding the use of DRS.
"This is a tough Test series being enjoyed by hundreds of millions of people, courtesy of two teams giving their all for their countries.
"The ACA feels that it is better for commentary to focus on the supreme contest rather imply a system of unfair play"