"I took an impact at the top of the foot and it was so sore at half-time that I felt sick," said the player of the match. "I thought it might be broken but with the tie still there to be won I carried on."
The tireless Fishlock was finally substituted 14 minutes from time with City's passage to the last 16 - where they will face Arsenal - all but assured. Despite losing an injury-time goal they beat the Belgian champions 3-1 on the night and 5-3 on aggregate.
"I'm really looking forward to playing Arsenal," said Fishlock, who is on loan from Seattle Reign. The Wales captain is also relieved she will be fit to lead her country into their World Cup qualifier against England next Saturday. City will be away to Arsenal on either November 9 or 10, with the return leg in Glasgow the following midweek.
As well as the numerous Scots involved in that showdown, the former City player Lisa Evans is in line to play for Turbine Potsdam in the tie of the round against 2011 and 2012 winners Lyon.