Dan Carter expressed his excitement at the prospect of returning to Racing 92 but conceded it was tinged with sadness following Pat Lambie's forced retirement.
The Top 14 club confirmed on Sunday that the former New Zealand fly-half would be reunited with the team until the end of the season, after it was announced last month that Lambie would have to step away from the game at the age of 28 due to a series of concussions.
Carter, part of the All Blacks' squads to lift the Rugby World Cup in 2011 and 2015, spent three seasons in Paris between 2015 and 2018, winning the Top 14 title in 2016.
"Excited to be joining my Ciel et Blanc brothers for the remainder of the Top 14 Season in France," Carter posted on Instagram on Monday.
"I'm coming back mid season as a Medical Joker. It was very sad to hear about @patlambie_'s decision to retire as he has done so much for international rugby.
"Thank you to my family for their continued support, and thank you to @racing92 for the opportunity. I'm looking forward to getting back on the pitch! #rugby #top14 #sports #france."
