But he was delighted with three players scoring for the first time as an inexperienced and unfamiliar line-up returned Australia to winning ways on Wednesday night.
After two losses to Brazil, nine players returned to their clubs in Europe including Steph Catley, Caitlin Foord and Ellie Carpenter.
Sermanni made seven starting line-up changes and young midfielder Daniela Galic, Natasha Prior and Sharn Freier made their first starts.
The Matildas looked set to canter to victory after Prior and Freier netted their first international goals, on their first starts, in the 10th and 12th minutes at AAMI Park.
But Taiwan scored their first goal against Australia since 2007, via Chen Jin-wen in the 34th minute, to spark the contest to life.
Bryleeh Henry (r) scored her maiden international goal just five minutes after coming on. (Morgan Hancock/AAP PHOTOS)
Australia dominated shots 25-9 but never looked comfortable until substitute Bryleeh Henry scored her first international goal - five minutes after coming on - in the 78th minute to seal the victory in front of 26,795 fans.
Sermanni admitted the Taiwanese goal had put Australia under unnecessary pressure after he'd been delighted with his team scoring twice early.
"As a coach, you would like to create more when you do that, but then you've also got to be pragmatic and practical," he said.
"We've had one training session on the day before the game with a significantly different group of players.
"And then you throw them on the field with a little bit of guidance, and you hope that things all come together.Â
"So you've got to look at the game in that way as well. And so I think overall, it was challenging to create chances, but that's not unexpected."
The result was soured by luckless midfielder Chloe Logarzo - playing her first Matildas game since tearing her ACL against Ireland in October 2022 - being forced off inside the first half-hour after a head clash.
The 29-year-old pleaded with Australia's medical staff to allow her to play on and was in tears when she was replaced by Alex Chidiac.
Sermanni didn't know yet whether a "devastated" Logarzo was concussed - which would also rule her out of the Matildas' second match against Taiwan on Saturday at GMHBA Stadium - with the doctors still looking at the midfielder after the match.
"She's got the old egg on the side of her head at the moment. She feels good," he said.
"Hopefully it's not too bad and hopefully she might come into discussions for the next game."
Freier was lively at wing-back, while Sermanni hailed central defender Prior and took heart from his inexperienced players scoring and his substitutes making an impact.
"The more people you get on the scoresheet, the better for energy," he said.
Tom Sermanni made seven changes to the Matildas starting line-up against Taiwan. (Morgan Hancock/AAP PHOTOS)
Australia took the lead from a short corner.
Emily van Egmond worked the ball to Logarzo, whose lofted cross across the box was flicked on by Daniela Galic, with Prior on hand to coolly score.
Two minutes later, Emily Gielnik forced a fingertip save from Taiwan goalkeeper Wang Yu-Ting who turned the ball onto the bar, but Freier was on the spot to head home.
For Taiwan's goal, Chan Pi-han launched a long ball for Chen, who turned Charli Grant inside-out then finished with aplomb.
History made 📖— Paramount+ Australia (@ParamountPlusAU) Chinese Taipei score against @TheMatildas for the first time in over 17 years through Jin-Wen and look at what it means to them!#AUSvTPE is LIVE on Paramount+ pic.twitter.com/EXL8fAIScHDecember 4, 2024
Australia sealed victory when Yallop crossed for Henry, who brilliantly headed home.
Leah Davidson came on for her international debut in the 80th minute as Australia closed out the game.
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