Retiring NRL star Johnathan Thurston announces newest addition to family

Retiring North Queensland Cowboys legend Johnathan Thurston has announced that he and his partner Samantha are expecting their fourth child.

Thurston took to Instagram to post a picture of the baby's ultrasound image.

"Our little surprise package!! Joining us Feb 2019," Thurston said in the caption.

The Thurstons currently have three daughters - Lillie (18 months), Charlie (3) and Frankie (5).

Thurston is set to play his final NRL game for the Cowboys against the Gold Coast Titans in front of a sold out, devoted Queensland crowd.