Ireland international Jared Payne has been forced into retirement with immediate effect after failing to recover from a head injury.
The 32-year-old sustained the blow when he represented British and Irish Lions during their tour of New Zealand last summer and has failed to make a recovery from it.
Payne will now work with Ulster as defence coach and will also link up with Ireland side to be part of their coaching panel for the summer tour of Australia.
"I had to come off [for the Lions v Chiefs] but I didn’t think anything of it, a little bit headachey and sore that week, but nothing too bad.
"Come the captain’s run day for the next game, I think it was the following Tuesday, I got home and got back on the bus and felt a bit travel sick, pretty yuck.
"Ever since then I haven’t been quite right.
"It’s been a bit stop-start. There’s been times when it hasn’t been too bad and other times when it’s been pretty bad.
"We’ve tried different things to get it right and been trying to get back but unfortunately nothing has cleared everything up just yet."
The New Zealand born centre was part of Super Rugby sides Chiefs, Crusaders and Blues before he switched to Ulster in 2011. He has won 78 caps for the Irish regional side apart from making 20 Test appearances for Ireland side between 2014 and 2017.
"While I will undoubtedly miss the buzz of running out with mates every weekend, I have to listen to the medical advice and unfortunately give up the dream.
"However, I've surprised myself how much I have enjoyed coaching and I'm really looking forward to getting my teeth into this role on a permanent basis."