Hull KR have sacked head coach Craig Sandercock with immediate effect.
The Robins announced the move on Thursday night and have put assistant Chris Chester in charge ahead of Sunday's home game against St Helens.
A statement from the club said: "The club has made the decision not to renew Craig's contract in 2015 and, with that in mind, have placed Chris Chester in charge of first-team duties initially until the end of the season whilst a full review of all off-field operations is carried out.
"The club would like to thank Craig for all his hard work over the last three years and wishes him well in the future."
Hull KR are currently outside the top eight in the First Utility Super League after winning just seven of their 19 matches so far this season.
Sandercock was appointed as the successor to fellow Australian Justin Morgan at Hull KR in October 2011 after being recruited from Newcastle IKnights, where he was assistant coach.
He was out of contract at the end of the season and was thought to be in talks over a new deal until recently.
Sandercock is the fifth coaching casualty so far this year after Salford, Bradford, Wakefield and London Broncos all made a change in the first half of the season.
Francis Cummins, the most recent departure from Bradford, is being linked with the vacancy.