Apprentice Oisin Murphy will join Andrea Atzeni as a retained rider for Qatar Racing.

Atzeni will replace Jamie Spencer as the No.1 jockey for Sheikh Fahad with 18-year-old Murphy, who rode in Australia during the northern hemisphere winter, the No.2.

Their positions come into effect from from January 2015.

Murphy, whose career took off with Andrew Balding, said he was looking forward to the challenge.

"I'm very fortunate to be given the opportunity to be a part of Qatar Racing," Murphy said on Twitter.

"I look forward to my role as second jockey in the coming season. I would like to thank Andrew Balding for his guidance and support during the past two seasons."

The 23-year-old Atzeni said it was an exciting time in his life.

"I feel very privileged to have been asked to ride as first jockey for Qatar Racing," he said.

"I am excited at the prospect and look forward to repaying the faith Sheikh Fahad and his brothers have shown in appointing me.

"In particular, I would like to thank Roger Varian and his wife Hanako for their support.

"I credit Roger with putting put me on the map, through horses such as Kingston Hill."

Spencer announced on Thursday he would be retiring from the saddle at the end of the current season to take up a new management role in Sheikh Fahad's operation.

David Redvers, racing and bloodstock manager to Qatar Racing, said both riders had been impressive this season.

"With Jamie retiring and Harry (Bentley) concluding his two-year contract, Sheikh Fahad is delighted to have secured the services of Andrea and Oisin for Qatar Racing," Redvers said.

"He has also asked me to reiterate his gratitude to both Jamie and Harry for all of their hard work, skill and professionalism.

"Harry will continue to ride for us when the opportunities allow."

"Andrea and Oisin have impressed us greatly this season and we are delighted to agree terms with them."

Sheikh Fahad is the owner of the recently retire Dunaden, winner of the 2011 Melbourne Cup and the Caulfield Cup the following year.