The All Blacks have already admitted the 53-year-old is on their list of targets as a potential replacement for head coach Steve Hansen, who will step down after the 2019 World Cup in Japan.

Gatland's Wales contract also expires after the next World Cup, leading Spencer to tip the former Ireland and Wasps boss to field a glut of coaching offers in two years' time.

"Set a Kiwi to catch a Kiwi," said Spencer, assessing Gatland's job as Lions boss on the 2017 tour.

"You have to be a very shrewd coach to come to New Zealand and achieve what the players achieved yesterday.

"I will tell you without doubt I think Warren Gatland is the best head coach in the world."

Gatland has now led the Lions to a series victory in Australia in 2013, and a drawn campaign with New Zealand this summer.

The ex-Waikato man insisted "never say never" when asked if he could lead the Lions to South Africa in 2021, but Spencer insisted Gatland will be inundated with job offers to follow his Wales tenure.

"Never say never about the Lions, but I think that a lot will happen in the next four years," said Spencer.

"I think Warren will be in very big demand all over the world. And that's his decision.

"I think Ian McGeechan said it several weeks ago, you can't hope to beat the All Blacks unless you understand their people and their culture, their way of life and the attitude to rugby.

"Warren does understand the New Zealand psyche and there are plenty of instances on tour when he has proven that.

"I don't want to take anything away from Wales, because Warren's got a job to do there.

"But I think his achievements on this tour have opened up the future for him."

Gatland entered the post-match press conference after Saturday's 15-15 draw sporting a red clown's nose.

In a light-hearted riposte to the New Zealand Herald caricaturing him as a clown, Gatland was finally able to hit back against treatment in the Kiwi media he felt had become too personal.

The Lions were able to turn what Gatland labelled a "targeted campaign" against him to their advantage, building a siege mentality among the squad.

The 24-21 second Test victory put the Lions in with the chance of a first Test series triumph in New Zealand since 1971.

But despite the three-Test series ending in a one-all tie, the tourists will depart Kiwi shores in high spirits and proud of their exploits against the back-to-back world champions.

Spencer insisted however that Gatland had not used any negative media coverage to ease the pressure on his players.

Asked if Gatland had jumped on the Kiwi media approach to shield his squad, Spencer said: "I don't think so.

"You talk to Warren regularly, he's a very straight guy.

"There's one or two things he'll want to get out in the press, and one or two he'll keep to himself.

"But he doesn't do things intentionally to either encourage or rile people.

"He was very interesting in the team talk to the boys yesterday.

"He talked to them all about having played big games in the past, being successful, so that they knew what was required.

"He talked about going after the All Blacks, not watching them play or altering our styles of play to meet theirs.

"We were going after them, they were going to have to cope with us, and that's what happened."