Crusaders assistant coach Brad Mooar will replace compatriot Wayne Pivac as Scarlets head coach after the 2019 Super Rugby season.

Pivac is set to replace Warren Gatland as Wales coach following the 2019 Rugby World Cup, with Mooar announced as Pivac's successor at the Welsh club on Monday night.

Mooar said he was excited by the chance to further his coaching career in the Northern Hemisphere.

GETTY IMAGES Former Auckland coach Wayne Pivac will be replaced by Brad Mooar at Scarlets when he takes up the Wales job in 2019.

"It's never an easy decision to step away from an environment that means so much to you and, come the end of the Super Rugby season, the moment will no doubt be bittersweet.

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"However, the opportunity to take on the role of head coach at the Scarlets is simply too good to pass up and is both an exciting challenge for myself, and a fantastic opportunity for my family to experience life on the other side of the world.

"Scarlets is a winning club with an extremely proud history, passionate fans, and is aspirational in its goals. It is humbling to be offered the opportunity to take the reins after the great work Wayne Pivac has led, as he moves on to the Wales job."

It will be Mooar's fourth and final season at the Crusaders next year.

Prior to that he was Southland coach, while in 2012 he moved to South Africa to coach the Eastern Province Kings to a Currie Cup Division 1 title, then became assistant coach of the Southern Kings Super Rugby side.

Crusaders head coach Scott Robertson said Mooar would be missed.

"Brad is such an important part of the Crusaders leadership team - he's intelligent, insightful and is hugely respected by the playing group and management alike.

"While we'll miss him, this is an amazing opportunity for Brad to step in to the top job as a head coach, and his Crusaders family will have plenty of motivation to send him out on the best possible note at the end of this season."