"He loves it - it's amazing," Newcombe said from his courtside seat in the Seven Network's commentary bunker.
The victory - featuring 28 winners, four service breaks and more than the odd signature "come on" - set up a second-round crack at Spanish eighth seed David Ferrer on Thursday.
If he finds a way to win that, Hewitt will be back at Melbourne Park on Saturday playing for a dream spot in the second week in his record-setting 20th consecutive Open campaign.
First, he must recover from Tuesday's sapping win.
The 2005 finalist needed two hours, 23 minutes to put away Duckworth and, apart from a brief reprieve in the second set, there was barely an easy moment.
Once the five-set king of tennis, Hewitt has lost his past six matches that have gone the distance and even his most loyal of fan must have been edgy when Duckworth led 4-2 in the third set.
But, not for the first time, the baseline warrior rallied back to win four straight games and raise the roof after clinching his first grand slam win since last year's Open with a trademark topspin lob on match point.
"This is what I'm going to miss most - this adrenaline buzz of coming out here," Hewitt said.
"Hearing Craig Willis announce you from Australia and the whole crowd erupts. It doesn't get any better than that."
Hewitt admitted it'd been difficult not to get distracted by the fanfare and emotion of the occasion.
"It was a tough situation to try and block out everything else that's going on," he said.
"I tried to prepare as much the same as normal and - playing Ducks (Duckworth) as well, who I've tried to help out for the last few years - that was really awkward.
"But I just came out and tried to stay in the moment as much as possible."
Hewitt's entire family - wife Bec, children Mia, Ava and Cruz, father Glynn and mother Cherilyn - were also on deck for his 50th appearance at Rod Laver Arena.
"It's been one of the most satisfying things of my career," Hewitt said.
"The kids are now old enough and they're going to have lifelong memories of dad being an old man and limping around on the tennis court.
"It's been a lot of fun. I'm really proud that the family - Bec and the kids - can enjoy this with me.
"Obviously, it's a really emotional time but we're just trying to enjoy this as much as possible."