The defending champion Bulls have been setting the Super Rugby stage alight this year, but it has been a change in attitude rather than a shift in tactics that has made them such a formidable force.

Second row forward Flip van der Merwe, speaking to rugby365.com ahead of their Round Six showdown with the Hurricanes on Friday, said nothing much has changed since they won their second Super title last year.

Many pundits have speculated about the reasons behind the Bulls' impressive early form - unbeaten with a full-house 20 points after four game, 199 points and 24 tries at an average of six per game - that see them not only top the standings, but also heading the stats count by some margin.

While the change in focus at the tackle/ruck situation has certainly contributed to the Bulls' try-scoring spree, Van der Merwe said they had not really changed their systems.

"We haven't changed anything," Van der Merwe told rugby365.com, adding: "As coach [Frans Ludeke] said at the start of the season, we must just do what we do that much better."

The burly lock, son of 1980s Springbok prop Flip van der Merwe, said every player is responsible to make the step up and lift his game a few percent.

"We all knew that Fourie du Preez has been good, but he is even better this year and Victor [Matfield] is good, but he is even more impressive this year," Van der Merwe said.

"Every player has taken responsibility for improving his own game and it is going well at the moment," he added.

The 24-year-old, who made his Super Rugby debut for the Cheetahs in 2007 before moving north to Pretoria in 2009, said it will be another huge step up against the Hurricanes on Friday - despite the Kiwi outfit's recent slump in form.

He felt they would be hurting after back-to-back defeats against the Cheetahs and Stormers and that the Bulls may well feel the brunt of the Hurricanes' anger as they try to put their campaign back on track.

"They remain a dangerous outfit," he told rugby365.com, when asked about the defeats on their South African safari.

"As we all know, New Zealand teams don't take too kindly to a beating and always bounce back.

"In addition, because the Bulls are the defending champions, every team want to have a go at us.

"That is why we have been working hard to raise our game this week."

And, like any New Zealand team, the Hurricanes are expected to be physical.

"They have a powerful set of forward and then they have those powerful-running backs that can attack from anywhere ... like Tamati Ellison and Conrad Smith.

"From broken play they are very dangerous and we'll have to be wide awake and on top of our game."

Van der Merwe, who had made only six Super Rugby appearances between 2007 and 2009 for the Cheetahs, has benefitted from the injury-enforced absence of Bakkies Botha and featured in every game this season.

Describing it as a "big opportunity", he admitted that the additional game time was unexpected.

"You always train and hope for your opportunities," he said, adding: "But I didn't expect Bakkies to be sidelined this ;long.

"However, I'm enjoying every moment and try to make the best of it."

The other positive is that he is learning from the best, playing alongside the likes of Matfield and another Bok veteran in Danie Rossouw.

"When I was at school, Victor and Bakkies were my heroes, now I am playing with them.

"At the moment I am living the dream and I am learning every day."

Van der Merwe's task of slotting in has been made that much easier by the fact that he has come into a winning culture.

"I said the other day, here [at the Bulls] you only have to worry about you own job.

"Every player is so good in his own position that you don't have to worry about anybody else. You can concentrate on doing what you have to do and do it well."