2. Schalk Burger – South Africa

Position: Flanker
Caps: 86
Test career: 2003–2015

“He just kept coming for me”

Schalk Burger’s relentless physicality left a lasting impression on both All Blacks legends.

McCaw said: “You can come up against another tough team but never feel like you have had a tough match against your opposite. But with Burger you knew where they are going to be and how hard they play near the ball.”

Carter remembered regularly finding himself in the Springbok flanker’s sights.

Carter said: “I kept looking at my All Black jersey wondering if I had a target like in the middle of the jersey or something because he kept coming for me.”

He added: “He just kept going. He didn’t stop. He was physical and just his leg drive was incredible. A real competitor and absolute top bloke off the field as well.”

Burger was named World Rugby Player of the Year in 2004 and later helped South Africa win the 2007 Rugby World Cup.

His remarkable career also included a comeback from a life-threatening illness before returning to international rugby.

1. George Smith – Australia

Position: Flanker
Caps: 111
Test career: 2000–2013

“I used to hate playing this guy”

Taking top spot is Wallabies breakdown master George Smith.

McCaw first encountered Smith before either had established themselves as Test rugby superstars – and immediately realised just how good the Australian was.

McCaw said: “Smith was always pretty tough. I remember playing him when I was in the under 19s against Australia and remember then thinking just what a good player he is. I’ve never seen a guy as gifted in all facets of the game.”

Carter was even more succinct.

Carter said: “I used to hate playing this guy because he was so bloody good. A true legend of the game.”

Smith earned 111 Test caps during an extraordinary international career and became one of the defining opensides of his generation.

His ability over the ball was legendary, but it was his complete skillset – carrying, passing, tackling and reading the game – that separated him from many of his contemporaries.

He was twice awarded the John Eales Medal as Australia’s outstanding international player.

Dan Carter and Richie McCaw both agreed on the greatest number 10 in rugby history