Australia lock Rob Simmons will leave the Waratahs at the end of the Super Rugby AU season and is set to join London Irish.
Simmons has won 100 caps for the Wallabies, but it remains to be seen if he has played his last Test after sealing a move to England.
The loss of the 31-year-old captain is a big blow for the Waratahs, where he arrived in 2018 following nine seasons with the Reds.
Simmons will join compatriots Nick Phipps, Sekope Kepu and Adam Coleman at ambitious Premiership club the Exiles.
He said: "It was a really tough decision [to leave] but after speaking with many people around me, I felt that now was the time to take the opportunity to play overseas.
"Timing with situations like this can't always be perfect, but the Waratahs have been fantastic in understanding my desire to take on a new challenge.
"I've loved my time in Super Rugby and the last few years with the Waratahs, it's a wonderful organisation and it's been an honour to lead this group throughout 2020.
"My team-mates and our management team have been tremendous over the last few years, there's a lot to be excited about here in New South Wales and I'm looking forward to seeing it unfold from afar."