London - Graham Henry warned Warren Gatland that coaching the British and Irish Lions was the "most demanding job in Test rugby" as his fellow New Zealander prepared to unveil his squad for Australia.
Gatland is due to name his party to face the Wallabies on Tuesday, hoping to succeed where Henry failed in 2001 by leading the Lions to a series win in Australia.
Henry, the first foreign Lions boss, made his name in Europe by coaching Wales - the team Gatland is currently seconded from in order to take charge of the combined side.
Twelve years ago the Lions lost a three-match series 2-1 - a defeat Henry, who in 2011 guided New Zealand to a Rugby World Cup triumph on home soil, said was down to his mistakes.
"I learned more from that experience as a coach than any other," Henry told Monday's Western Mail, Wales' national daily newspaper.
"I did not do things as well as I should have and made some wrong decisions. If I had got them right, we would have won the series.
"I thought I could do the job but I was green as an international coach then. I now know that the position of Lions head coach is the most demanding in Test rugby," he added.
The Lions, who traditionally tour one out of South Africa, New Zealand and Australia every four years, have not won a Test series since overcoming the Springboks in 1997.
However, Henry was confident that in Gatland, a former coach of Ireland as well as an assistant Lions coach in South Africa four years ago, the combined side had "exactly the right man" in charge to end that losing streak.
"Warren is an outstanding coach with a wealth of experience," said Henry. "He has led Wales to a couple of Grand Slams and they retained the Six Nations this year. I know he was not around but it was his set-up... He understands what the Lions are all about. He is exactly the right man for the job."
In comparison to New Zealand and South Africa, Australia have long been regarded as the Lions' most 'beatable' opponents.
However, Henry warned the 2013 Wallabies would be no pushovers.
"You only have to look at this year's Super Rugby to see that Australian players have a different stride," he said.
"Their teams have played some exceptional rugby and what everyone should always be aware of is what a Lions tour means to Australia, New Zealand and South Africa."
Sam Warburton has been tipped to be Gatland's Lions captain, even though he apparently declined the honour of leading Wales in their Grand Slam-clinching win over England after being injured earlier in the Six Nations.
Former England and Lions centre Jeremy Guscott, though, has questioned whether back-row Warburton, who finds himself battling for a Lions place in what appears to be the most keenly contested area of the squad, had the right credentials to skipper the team.
"Personally, I just don't think Sam's ready to be captain of the Lions," Guscott told BBC Sport. "Warburton is not nailed on to be in that side."
Instead Guscott said Brian O'Driscoll, whose time as the 2005 Lions captain in New Zealand was cut short just minutes into the first Test when the Ireland centre suffered a tour-ending injury following a 'spear' tackle, should lead the Lions this year.
"The stand-out candidate in my view is Brian O'Driscoll because he's been on a few (Lions) tours."
The Lions begin their tour against the Barbarians in Hong Kong on June 1, with the first of three Tests against Australia in Brisbane on June 22.