The defender lashed home the winner in the first half of extra time to book Leanne Crichton’s side’s spot in Saturday’s final against Ajax.
The Light Blues had fallen behind to Isabella Briedle’s opener on 57 minutes, only for captain Nicola Docherty to come up with a stunning volley with nine minutes remaining to take the game to extra time.
Austin then finished off a superb counter-attack to secure the victory, and the stopper says she was thrilled to see her strike hit the net.
Speaking to RangersTV, she said: “I am delighted; you could tell by my celebration I was buzzing.
“That was the first time I have started a Champions League game, so I wanted to make a mark, and I think I did that.
“I think in the end we deserved it. I didn’t think we played our best in the first half, but in the second we made up for that.
“We knew we all had the character to win the game even when we were 1-0 down.
“It was difficult; they were very physical, and we had to adapt to that, but I think the girls were great.
“We know we have a job to do, but we help each other and guide each other.
“We played good opposition in Birmingham and Newcastle in pre-season. In these games we didn’t have a lot of the ball, but I think those tests have set us up well for these types of games.”
The Gers - who had Eva Hendle sent off with five minutes left - will now face the Dutch giants for a place in the next round of the elite tournament.
No matter the result, the Light Blues will continue their European adventure with a spot in the Europa Cup second qualifying round.
Austin isn’t even thinking of that as she insists the squad’s only focus is trying to get the better of Ajax at Petershill on Saturday.
She added: “We have to recover and then look at what we can do better and what we did well.
“The result means we stay in Europe, but the main aim is that we go further in the Champions League and that’s what we want to do now.”
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