Despite having trailed during extra time, Atletico rallied to register a 3-2 win at the home of the Premier League leaders, earning the club a place in the Champions League quarter-finals.
Felix, who played for over 100 minutes on Merseyside, has acknowledged that he had been left stunned by the reaction to Liverpool scoring earlier on the night.
The Portuguese is quoted by AS as saying: "It was incredible. I shouldn't say it, but when they scored, seeing the stadium and their way of celebrating.
"I had seen this on television, but seeing it live and being within this great atmosphere. Hardly anyone wins here and we are so happy."
Felix joined Atletico last summer after allegedly rejecting the opportunity to sign with either Manchester City or Manchester United. body check tags ::