Justin Marshall said New Zealand is in a state of shock following the death of Jonah Lomu and credited the All Blacks legend for taking rugby union "into a different stratosphere".
It was announced on Wednesday that Lomu had passed away suddenly in his homeland at the age of 40.
The former wing, who scored 37 tries in 63 matches for his country and is the joint-leading scorer in Rugby World Cup history, was diagnosed with a serious kidney condition back in 1996.
Lomu's career was cut short due to the illness, but his sudden death - which came just after he returned from the World Cup in England - was unexpected.
Marshall paid tribute to his former New Zealand team-mate, who he credited for taking the sport to another level.
"It's been a really difficult day here as a former team-mate of Jonah's, but also for the country in general." Marshall told Sky Sports.
"Jonah Lomu was a legend of the game here and the general shock of his passing his affected everybody, not just former players and current players but the general public.
"He is an icon of the game. For me, the thing that he did was reassure me. When I looked across the changing room, or around the changing room and training pitch and then it a Test match and I saw Jonah Lomu in that number 11 jersey it just reassured me that I was in the presence of somebody that could do something great; something spontaneous and spectacular.
"When you've got that in your arsenal as a team you could be having a bad day, but someone like him when he gets his hands on the ball could flip a bad day into being a winning day and there's not many players in the world who can do that.
"Jonah Lomu came along in the 1995 Rugby World Cup and launched the game into a different stratosphere; into America, into Asia.
"You could say when rugby had to go through that transition, that was probably more important than winning a World Cup."