Tuivasa-Sheck's current contract with the Warriors runs out after this season.
The Aucklander is on the UFC 219 card on New Year's Eve in Las Vegas, a rare achievement for a Kiwi.
Reid Harker won't do it on his own though, with a Kiwi legend guiding him off the track as well.
Sir John filled the roles of a rugby player and headmaster in his life, but what he did for those around him in those roles is what set him apart.
The All Blacks have named a strong line up to face Manu Samoa but are still keeping tabs on the Lions.
The trio could be in line to start a Test match together when the All Blacks take on Samoa on Friday.
1 NEWS understands Parker will work solely with Higgins after DUCO's split.
Gatland's Lions play the Blues next Wednesday but his son Bryn will turn out for the Auckland side.
The British and Irish squad will touch down in Auckland today. You can watch a live stream on 1 NEWS Now.