Wellington - Jerome Kaino always knew that coming back to New Zealand from Japan in an attempt to make the All Blacks again would be tough, not just because of the quality of fellow loose forward contenders.
The rise in intensity from Japan's top flight to the southern hemisphere's Super Rugby competition has also been an eye-opener.
"I wouldn't say it has been easy," the Auckland Blues forward said at All Blacks' training in Wellington on Monday.
"It's a lot harder getting up a day after a game and having to bounce back and then get prepared in a week.
"For me it was a lot harder being in a game and having to hit a ruck with everything you've got, then to hit the next ruck with the same amount of intensity.
"The same goes with the tackle and carrying the ball.
"In Japan you could switch on and off with what you do physically but here you just can't do that."
Kaino, one of the All Blacks' standouts when they won the 2011 World Cup, returned to the Blues this year after two seasons in Japan.
After coming off the bench in round six against South Africa's Cheetahs, the 31-year-old has started all seven of the Blues' games since, playing every minute in six of them.
Should Kaino be named on Sunday by All Blacks coach Steve Hansen in the 31-man squad for next month's test series against England he will join an exclusive club.
Kaino would be the third All Black, and first forward, to have left New Zealand rugby and returned to the country to force his way back into the national team since the game went professional in 1995.
The two previous players, Leon MacDonald and Luke McAlister, were both backs and only MacDonald would be considered to have made a successful return.
MacDonald played four more seasons for the All Blacks after returning from Japan in 2005.
McAlister, who left after the 2007 World Cup, returned to New Zealand in 2009 and played eight tests, five of them from the bench but was not considered again.
"I still believed that I had a bit of rugby left in me," Kaino said.
"The only nervous thing I had was where I fit in terms of the flankers in New Zealand and what the rugby was going to be like."
Kaino's confrontational presence balanced the loose forward mix with openside flanker Richie McCaw and number eight Kieran Read at the 2011 World Cup and his form for the Blues suggests he has lost none of that edge.
Tipping selection in his favour is that he has started four of his last seven games at number eight - a position Hansen has worried about covering, with first-choice Read under a cloud.
"I'll be happy if I'm there if he's not available," Kaino said of Read, who may be ruled out of at least the first test in Auckland on June 7 due to a lack of match fitness after suffering concussion more than five weeks ago.
"(But) I'll play anywhere in the loose forwards to get a spot in the team."