Teenager Lily Murphy scored her first senior goal as Manchester City eased to victory against St Polten, but the win was overshadowed by Alex Greenwood being taken off on a stretcher.
Second-half goals for Murphy and Kerstin Casparij maintained City's 100% record in the Women's Champions League this season and keeps them top of Group D, three points ahead of defending champions Barcelona.
The hosts found plenty of joy down the left-hand channel as forward Murphy - making her first start in the absence of Khadija Shaw, who BBC Sport understands was left out as a precaution - attempted to make the most of her full first-team debut.
The 18-year-old should have scored after just five minutes when Mary Fowler played her in behind the backline, but the teenager's low shot was saved by the foot of Carina Schluter.
Laura Blindkilde Brown, Yui Hasegawa and Jess Park repeatedly won the ball in midfield to keep the visitors under constant pressure, though City's momentum was halted when Greenwood appeared to injure her knee in a challenge with Melanie Brunnthaler.
The defender immediately called for medical attention and was taken off on a stretcher to a standing ovation.
Boss Gareth Taylor said he didn't know the extent of England international Greenwood's injury but she would be a "huge loss".
"We will just have to assess, like with all the many other injuries we have got," he added. "We have two games to get through [before the winter break], we will check in on Alex and see how she is, but it takes a lot for Alex to come off."
City were playing without longer-term absentees like Vivianne Miedema, Lauren Hemp and Naomi Layzell, with Chloe Kelly and Shaw also missing out.
"We seem to be losing big players," Taylor added. "Miedema, Lauren Hemp, Layzell, Bunny Shaw. If it's Alex it is going to make it really difficult for us.
"But the girls are good in that sense. The recovery levels are good and, hopefully now, once we get this break we have a little bit of time and don't miss these players for too long."
St Polten managed to gain some territory towards the end of the half, but they needed a superb goalline clearance from Chiara D'Angelo to deny what would have been a tap-in for Fowler.
City reasserted their dominance in the second half and took a deserved lead when Murphy - a childhood City fan - converted Aoba Fujino's teasing cross at the back post for her first goal for the club.
Fujino continued to wreak havoc down the right wing and provided a near-identical assist 11 minutes later, though this time Casparij was the scorer.
Murphy could have scored her second of the evening but curled wide after racing into the box from the left flank.
In the night's other game in Group D, Barcelona defeated Hammarby in Stockholm.
City will win the group and receive seeding in the quarter-final draw so long as they do not lose to Barcelona next week by a scoreline greater than 2-0.
Although City moved a step closer to their target of winning the group, it was a mixed evening for Taylor's side.
Greenwood's injury did not look good at all. Replays showed her knee twisting as she stepped in to win the ball, and the 31-year-old immediately called for attention.
Not only is she City's captain, but Greenwood is one of the best ball-playing central defenders in the world. Her ability to start attacks from the back is key to the way Taylor wants his side to play.
Any long-term absence could have a serious impact on City's prospects in the Women's Super League and Champions League, as well as being a blow to England in the months leading up to Euro 2025.
It wasn't all doom and gloom though. There were joyous scenes on and off the pitch when youngster Murphy scored her first goal for her childhood club on her first senior start.
"It's unreal," Murphy told BBC Sport afterwards. "Sharing this moment with my family who were watching me in the stands, it's unreal."
It was a good night for City's other youngsters too, with Blindkilde Brown (21) playing the full 90 minutes, while Gracie Prior (20) and Codie Thomas (18) came off the bench.
Another positive was the performance of Fujino, whose two assists were the two real moments of quality City produced. With Lauren Hemp and Chloe Kelly both currently sidelined, the Japanese winger, 20, is hitting her stride just when City need her.
And there was a first club goal too for Casparij, who could offer another attacking option for City.
"We've revealed the new Kerstin more recently," City boss Taylor told TNT Sports.
"We are trying to play to her strengths, playing her higher up the pitch. She is a very good crosser of the ball.
"I was surprised when I saw the goal going in. I was like, 'wow, what is she doing up there?'. She is making an impact on games now and that is what we knew she could do."
After the opportunity to rate players has closed, the score displayed represents the average from all the submissions by BBC Sport users.