Ange Postecoglou admits he harboured doubts over Celtic's hunger to repeat their title-winning feat of last season. He needn't have worried.
Celtic are champions again after an outstanding campaign, retaining the trophy with four games to spare thanks to a 2-0 win over 10-man Hearts.
The treble is also within touching distance, and Postecoglou marvelled at the "absolutely ridiculous standard" his squad have set.
"I'm just really proud," he said.
"Having success last year, you always worry as a manager - are they going to be as hungry? From the first day, they haven't let up and it's a credit to every one of them.
"I thought we needed to be a better team this year to defend our title because, particularly knowing we were going to be in the Champions League, you shouldn't underestimate the physical and mental toll that takes out of you.
"Through that time our league form was outstanding. That's because the whole group were prepared to drive through that our main goal of being champions again was never going to be derailed.
"I haven't had to intervene at all in terms of making sure we're back on track. We've just been relentless. It's been an outstanding season."
Having overhauled the squad and overcome a challenging start to win the title and League Cup in his debut year, Postecoglou has continued driving Celtic forward this season.
They have suffered one domestic defeat, away to St Mirren in September, which remains their sole loss in the past 67 league matches.
The title is now in the bag, but records remain up for grabs. Should Postecoglou's men win all four remaining games - starting with next weekend's trip to Ibrox to face Old Firm rivals Rangers - they will set a new Scottish top-flight points milestone of 107, eclipsing Brendan Rodger's treble-winning Invincibles of 2016-17.
And with Inverness Caledonian Thistle in next month's Scottish Cup final all that stands between Celtic and a fifth treble in seven seasons, Postecoglou is adamant they will not be easing off.
"We still have four games to go and a cup final to prepare for," he added. "It's not over and we want to finish our season strong. These guys won't let their standards slip."
'I'm emotional'
Feted by the Celtic support, Postecoglou has won four out of five domestic trophies, and his exploits in Glasgow continue to see him linked with jobs in England's top flight.
Another crack at the Champions League beckons next season, and the 57-year-old Australian is happy to live in the moment as he paid tribute to the support of his family and friends.
"I rarely look beyond what's in front of me," he added. "We'll enjoy today because it's a hard-earned championship to win and we've done it in unbelievable style. I'll reflect on what's next after the cup final.
"I am [emotional] because you put a lot into it. I realise I am doing what I love and I am pretty good at it but it doesn't happen in isolation.
"The people around you, whether it's my family, my wife and kids, my friends, and the support I have had inside and outside the football club, you want to pay that back as well.
"All the sacrifices people make and the commitment and support they give me, it makes you emotional to think about."
