Zenit star Witsel in awe of Liverpool fans
Zenit lost 3-1 on the night, but still progressed on aggregate.
Witsel told UEFA.com: "It was crazy - we had a lot of pressure against us with the fans. They gave a power to Liverpool - it was not easy.
"After they scored the third anything could have happened but we were strong and we're happy because we got the qualification.
"I played here with Standard and it was crazy like tonight."