Coach Michael Cheika’s hardcore approach to fitness is proving one of the secrets behind the NSW Waratahs’ transformation into Super Rugby title contenders.

Wallabies No.8 Wycliff Palu has revealed the unglamorous secret behind the NSW Waratahs’ transformation from perennial under-achievers to Super Rugby title contenders.

Palu says coach Michael Cheika is training the Waratahs so hard it’s scary.

But the brutal sessions are paying off, with the Waratahs powering up to fourth position overall and into pole position to secure Australian conference honours with five rounds remaining before the finals.

The Tahs boast the best defensive record in the competition, a reward for their dedication to fitness as much as Cheika’s decision to employ a fulltime defence coach in former Wallabies centre Nathan Grey.

“Every time I come to training, I get nervous,” Palu said on Tuesday.

“You know it’s going to be a pretty tough session. (But) when you’ve got Cheik right behind you, it’s pretty easy to get motivated.

“All the boys here are pretty young, so they don’t really feel it.”

After completing his first 80-minute performance in a stop-start season disrupted by injury and the death of his father, 31-year-old Palu admitted he was “sucking in a bit” against the Lions on Sunday.

The big No.8 said Cheika’s hardcore approach, particularly the full-contact, game-like Tuesday sessions, had steeled the Waratahs for match day.

“Once Tuesday’s over, you’re kind of halfway there,” Palu said.

“When you get to the game, you go `Yes, finally’.

After overhauling the side’s attacking structures in his first season at the helm, Cheika’s emphasis this season has been on defence.

And while attacking aces like Wallabies trio Israel Folau, Kurtley Beale and Adam Ashley-Cooper have been credited with reviving the Waratahs’ fortunes in 2014, Grey is an unsung hero.

“He’s done a very good job around that defence and contact work. It’s obviously been an area where we’ve focused on to improve,” Cheika said.

“We’ve still got a fair way to go in relation to being watertight but, for a team that plays like us, it’s a good insurance to have if you’re defending well.”

Palu said in particular Grey’s strong focus on defensive line speed at training was having a big impact in matches.

“He drills it in pretty hard every week,” Palu said.

“It’s probably consciously in everybody’s head. When you’re pretty tired out there, as long as you’re moving up.”

With a game in hand on Australian conference leaders the Brumbies, the Waratahs regained control of their finals destiny with their bonus-point win over the Lions.

But having come unstuck against the Rebels in Melbourne last year, the Tahs are wary of another ambush on Friday night.

“Obviously we need to be ready to be physical,” Cheika said.

“They’re obviously playing well. They got a good result last week (against the Queensland Reds) and they’ll be full of confidence.”