The 18-year-old, who signed her first professional contract last week, opened her City account when she tapped home Aoba Fujino’s cross to hand us an early second half lead.
Kerstin Casparij then made it two just after the hour with her first goal in Blue when she met another Fujino ball in from the right.
There was a worrying sight on the half-hour mark as captain Alex Greenwood left the field on a stretcher, but City responded well to set up a grandstand finish to Group D away to second-placed Barcelona next week.
What happened
City were already assured of a spot in the quarter-finals ahead of kick-off, but were on top from the get-go in search of maintaining our 100% record on a chilly Joie Stadium evening.
Murphy was first to test Carina Schluter with an effort from a tight angle inside the opening five minutes, but the Blues were struggling to translate that possessional dominance into genuine clearcut chances.
At the other end, St Polten’s Sophie Hillebrand went closest for the visitors, firing a speculative effort from distance over the City bar following a corner.
Soon after that there was a concerning sight for the Blues as Alex Greenwood went down after a clash of knees with Melanie Brunnthaler.
The captain was brought off on a stretcher just after the half hour in some discomfort, replaced by Laia Aleixandri in the heart of the defence.
That setback took the sting out of the tie as half-time approached, though Alanna Kennedy would surely have grabbed the opener for City had she made clean contact on a deep free-kick into the St Polten box.
But Gareth Taylor’s side looked sharp after the break, and it wouldn’t take long for the opener to follow from 18-year-old Murphy.
Gambling on a low ball into the St Polten area by Fujino, the attacker tapped home into an empty net before being mobbed by her team-mates.
The youngster had been one of the Blues’ most lively players and you could see the confidence oozing from her after that special moment.
A teasing ball from the teenager into the far post towards Casparij on the hour almost yielded a second goal, but the full-back’s header bounced wide.
Murphy’s pace was causing problems down the left, and she almost doubled the lead when curling an effort just off target from Yui Hasegawa’s ball in behind.
But number two would follow from the opposite flank, with Casparij opening her City account just after the hour.
Fujino was once again the architect, with her dangerous pass across the face of the St Polten goal met by the defender who duly did the honours.
In an almost carbon copy of her chance around ten minutes prior, Murphy once again went incredibly close to another goal, curling an effort agonisingly wide from the left on 75 minutes.
Jess Park was next to go close, sending a dipping right-footed strike just over the St Polten bar from distance as the game ticked into the final ten minutes.
But City would have to settle for the two-goal advantage, making it nine wins from nine in all competitions on home soil in 2024/25.
What it means
City sit top of Group D with a 100% record from our five matches so far.
We’re three points ahead of Barcelona and will finish in first place should we avoid a defeat by two goals or more in our final Champions League fixture against the reigning champions.
How we lined up
Ayaka Yamashita started between the sticks, shielded by a back four of Kerstin Casparij, Alanna Kennedy, Alex Greenwood and Leila Ouahabi.
Yui Hasegawa sat at the base of the midfield, giving Jess Park and Laura Blindkilde Brown opportunities to get forward and join the attack.
At the sharp end, Aoba Fujino and Lily Murphy started on the flanks with Mary Fowler leading the line.
City XI: Yamashita, Casparij (Prior 77’), Kennedy, Greenwood (C) (Aleixandri 31’), Ouahabi (Thomas 77’), Hasegawa, Park, Blindkilde Brown, Fujino, Murphy, Fowler.
Subs: Keating, Roord, O’Carroll.
St Polten XI: Schluter, Mattner (Schumacher 72’), Johanning, Balog, Touon, D’Angelo, Dubcova (Madl 46’), Hillebrand (Meyer 72’), Mikolajova, Brunnthaler (Glibo 79’), Melike Pekel (Zver 59’).
Subs: Sieger, Abiral.
Up next
City are back in Barclays Women’s Super League action this weekend as we travel to Merseyside to face Everton on Sunday 15 December.
Kick-off at Walton Hall Park is set for 12:30 (UK), before a trip to Barcelona on Wednesday 18 December (17:45 kick-off) to round off 2024.
News about Man City v St Polten
Taylor provides Shaw and Greenwood update
Gareth Taylor has revealed that Khadija ‘Bunny’ Shaw is likely to be sidelined until the new year and that Alex Greenwood’s condition will be assessed. Read more
Highlights | City 2-0 St Polten
The best of the action from our UEFA Women's Champions League clash with St Polten. Watch more
Pitcam Highlights: City 2-0 St Polten
Relive City's latest UEFA Women's Champions League Group D clash from our unique Pitcam angle. Watch more
Full-match replay: City v St Polten
Relive the full 90 minutes of our UEFA Women's Champions League clash with St Polten on CITY+. Watch more
“I’m so proud”: Murphy reacts to first City goal
Lily Murphy says scoring her first City goal feels particularly special due to her lifelong affinity with the Club. Watch more