Richie McCaw faced some of rugby's fiercest forwards during his remarkable career. But when the All Blacks legend was asked to name his toughest opponent, one Australian stood out.

The two-time Rugby World Cup winner spent 14 years battling the world's best back-row forwards.

From England's Lewis Moody to South Africa's Schalk Burger, McCaw came up against some extraordinary players.

The former All Blacks captain has spoken openly about the men who tested him most.

We've brought together five flankers he praised during his career, including the Wallabies legend he identified as his toughest opponent.

The countdown is RUCK's editorial order, rather than a ranking made by McCaw himself.

5. Lewis Moody (England)

England's famously fearless flanker was nicknamed Mad Dog for good reason.

Moody never took a backward step, whether chasing a loose ball or throwing himself into a tackle.

A member of England's 2003 Rugby World Cup-winning squad, he went on to captain his country and win 71 Test caps.

McCaw had enormous respect for his all-action approach.

Speaking about Moody, he said:

“Moody was a little bit different to most flankers”

McCaw also praised his willingness to throw himself into challenges, his ball-carrying and the pressure he could put on opposition backlines.

4. Thierry Dusautoir (France)

Few players caused the All Blacks as many World Cup headaches as Thierry Dusautoir.

The France legend was outstanding when Les Bleus stunned New Zealand 20-18 in the 2007 quarter-final.

Four years later, he almost broke All Blacks hearts again.

Dusautoir scored France's only try in the 2011 final as New Zealand survived an enormous scare to win 8-7.

McCaw knew exactly how dangerous the Frenchman could be.

“He was always pretty big defensively and in the breakdown area. A menace”

McCaw also told Rugby World that he would have liked to play alongside Dusautoir.

The Frenchman was named World Rugby Player of the Year in 2011.

3. David Pocock (Australia)

David Pocock versus Richie McCaw was about as good as it got for breakdown enthusiasts.

The Zimbabwe-born Wallabies star developed a reputation for winning turnovers and making life miserable for opposition forwards.

His strength over the ball was extraordinary.

McCaw was full of praise when discussing Pocock on the All Blacks podcast.

“If you gave him even just a split second to get in there, it was almost impossible to move.”

The former New Zealand captain admitted the All Blacks spent considerable time working out how to limit Pocock's influence.

Pocock won 78 caps for Australia and helped the Wallabies reach the 2015 Rugby World Cup final.

2. Schalk Burger (South Africa)

This was never going to be a gentle afternoon.

Schalk Burger was one of the most physical forwards of his generation and a central figure in the Springboks side that regularly went toe-to-toe with McCaw's All Blacks.

The South African combined brutal tackling with remarkable mobility and skill.

McCaw knew what awaited him whenever Burger was on the opposition teamsheet.

“A violent brute at times.”

The pair also played together for the Barbarians in 2008.

Speaking to Rugby World, McCaw described Burger as a thoroughly likeable character off the pitch but a fierce competitor on it.

Burger won World Rugby Player of the Year in 2004 and helped South Africa lift the 2007 World Cup.

He finished his international career with 86 caps.

1. George Smith (Australia)

There could only be one man at the top.

George Smith was the Australian who repeatedly pushed McCaw to his limits.

The Wallabies openside was a master of the breakdown, combining outstanding technique with an ability to read the game.

McCaw first encountered Smith at under-19 level and immediately recognised his quality.

Their rivalry continued for years, with the pair regularly meeting in Test rugby and Super Rugby.

When Rugby World asked McCaw to name his toughest opponent, his answer was immediate.

“George Smith.”

The former All Blacks captain explained why the Australian stood out.

“Every time I played him it was a tough, tough battle.”

McCaw also praised Smith's intelligence and his ability to influence matches.

Smith won 111 caps for Australia and enjoyed a remarkable professional career that continued long after his international retirement.

For McCaw, few opponents presented a greater challenge.

Five extraordinary flankers. Four different nations. But only one man earned McCaw's ultimate respect. Would George Smith top your list?

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