The popular British player, who already seems a crowd favourite in Auckland, was pushed hard by Czech teenager Linda Fruhvirtova, eventually prevailing 4-6 6-4 6-2 in 2hr 38min.
Raducanu, who hadn’t played a competitive match in three months, needed all of her fighting qualities, in a match extended by two rain delays.
"It was a really challenging match," Raducanu said.
"We got off the court like 7pm and we went on at 3pm. So for four hours, it was pretty tough and testing with the conditions."
The 2021 US Open champion looked out of sorts early in the blustery wind, and was a set and a break down before she clicked into gear.
Once she did, it was a delight to watch; powerful aggressive shot-making from the baseline and some lovely touches at the net.
And boy, was she popular.
That was emphasised by the huge welcome, with some fans rising to their feet as she walked on to centre court for the first time and continued throughout, with a thunderous applause as she clinched her fourth match point.
"I was loving it," Raducanu said.
"I was very, very surprised, but I was absolutely here for it. I felt like I was playing in the UK and everyone was behind me."
Raducanu added that the double rain delay was a novel experience.
"I don’t think it’s ever happened to me," Raducanu said.
"It was testing; just to stay focused for that amount of time and not switch off and then stopping and then starting again."
The British player captured the imagination of the tennis world with her incredible 2021 US Open triumph, as a qualifier ranked No150 and that fascination has never gone away, despite mixed results since.
Her 2022 season was hampered by a wrist injury and yesterday’s match was her first since early October.
Fruhvirtova is one of the hottest prospects around, rising from No 296 to No 79 last year, taking out the Chennai title in the process.
She showed why early, with some powerful winners, with Raducanu under more pressure on serve.
After rain intervened at 4-4 40-40 on the Fruhvirtova serve, the Czech player showed her mettle to hold, defending two break opportunities.
That profligacy from Raducanu proved costly, as she dropped serve in the next game to lose the first set, with unforced errors costly.
The 20-year-old looked in deep trouble at 2-0 in the second set — after losing eight points in succession — and looked across to her coaches in frustration.
But she found something, reeling off four successive games, breaking the European twice.
"I was like, you need to stop this and just pick it up ... like be more aggressive and swing more freely," Raducanu said.
After struggling for most of the afternoon, Raducanu was back in the groove, with a jubilant fist pump as she held for 4-2. Fruhvirtova maintained her levels — forcing Raducanu to hit a sublime backhand winner to avoid a break back — before the British player closed out her second set point.
Another rain delay threatened to stymie Raducanu’s momentum, but she continued in style, sprinting to a 5-0 lead in the final set.
"I was really pushing it. I was pleased with how mentally stable I was."
Fruhvirtova saved three match points in a marathon seventh game before Raducanu finally clinched the contest, looking to the skies with a mix of relief and happiness.
"It’s hard," said a disconsolate Fruhvirtova.
"It was very close. She started to go for it and that made a difference."
Raducanu will face world No 134 Viktoria Kuzmova in the second round, after the former ASB Classic semifinalist upset fourth seed Bernarda Pera 6-4, 6-4, in a match carried over from Monday night.
Results:
Singles: Viktoria Kuzmova (Slovakia) beat Bernarda Pera (United States) 6-4, 6-4; Julia Grabher (Austria) beat Tereza Martincova (Czech Republic) 5-7, 6-1, 6-2; Venus Williams (United States) beat Katie Volynets (US) 7-6, 6-2; Emma Raducanu (Great Britain) beat Linda Fruhvirtova (Czech Republic) 4-6, 6-4, 6-2; Anna Blinkova (Russia) beat Elisabetta Cocciaretto (Italy) 6-4, 4-6, 7-5.
