Waratahs defense coach Nathan Grey

He is renowned for arguably changing the course of the 2001 British and Irish Lions tour in the Wallabies’ favour by concussing key English flanker Richard Hill, but now Nathan Grey is devising more cerebral tactics to knock the Crusaders of out whack.

Grey’s elbow to the temple of the Lions blindside in the 32nd minute of the second test in Melbourne was credited with shifting momentum against Graham Henry’s team who were unable to recover from the loss of the inspirational Hill for the remainder of the three-test series.

The 39-year-old doesn’t like to dwell on his airborne assault at Docklands (now Etihad) Stadium – it took until the Lions’ next tour to Australia last year for the hard-hitting midfield back to revisit a controversial incident that paled only in comparison to Duncan McRae’s unprovoked attack on Ronan O’Gara in the tour match against New South Wales.

When he was finally coaxed to reflect on the Wallabies series-levelling 35-14 victory, Grey said: “I will take it as a compliment if they think I can influence a test match that much.”

Grey has also kept a low profile in the lead-up to Saturday’s Super Rugby final with the Crusaders at ANZ Stadium – though again his impact has been a focal point.

A key member of Michael Cheika’s coaching set-up alongside fellow assistant Daryl Gibson, Grey has frequently been mentioned as players explain how the Waratahs have closed in on a maiden championship.

Alofa Alofa credited the defence coach with improving his game during his first Super Rugby season while, at the other end of the experience spectrum, veteran hooker Tatafu Polota-Nau said Grey prolonged his injury-ravaged career by adjusting his tackling technique and work at the breakdown.

Grey, who played the last of his 35 tests in the Wallabies’ World Cup semifinal win over the All Blacks in 2003, made 94 appearances for the Waratahs, service notable for his uncompromising one-on-one defence.

“He was going at Mehrts (Andrew Mehrtens) so I was pretty safe,” Gibson, smiled, when recalling the seasons when he and Grey marked each other in midfield at Super Rugby and test level.

This week Mehrtens’ successor at the Crusaders, Dan Carter, has been a target for Grey as he coordinates a plan to limit the effectiveness of the All Blacks maestro, who is occupying his old No 12 position.

At the start of the Waratahs’ build-up to their third appearance in a final, first five-eighth Bernard Foley said Grey would be strategising to apply pressure on the Crusaders’ playmaker.

“He always likes to keep attacks on edge. He has a number of little tricks he likes to play,” Foley said.

Grey has been credited with turning the Waratahs into the best defensive team in the competition this season an accolade to match their rating as the most prolific attack.

The Waratahs also boasted the tightest defence in 2011 then slipped to ninth on the ranking in 2012 and 11th last year.

That slide prompted Cheika to bring Grey back “home” from Melbourne here he was overseeing the defence performance, contact skills and then attack at the Rebels since Australia’s newest franchise joined Super Rugby in 2011.

“We specifically sought someone to come and dedicate himself to that defence and contact area. It’s something we knew we needed to improve if we wanted to be real competitors,” said Cheika.

Grey’s input has certainly satisfied that aim with the Waratahs boasting an array of defensive statistics that suggest the Crusaders could battle to secure their first title since 2008.

They have surrendered only 16.4 points per game throughout the season – while racking up a touch under 30; the 25 tries scored by the opposition is another benchmark.

The Waratahs have not conceded a four-try bonus point all year and since the Hurricanes produced three tries in the first half of their clash in Sydney on May 3, they have conceded just seven in seven games.

In last Saturday’s semifinal they kept the Brumbies scoreless after halftime despite absorbing 20 minutes of concerted attack from the 2013 runners-up.

And notably the Waratahs’ line has only been crossed five times during the final quarter of their games, proof they are committed to defending for the full 80.

“We’ve been good this year in the back end of the halves, especially the second half,” said captain Michael Hooper.

“It’s an area we’ve improved in. We sort of see them as the big minutes in a game.”