Question: How many teams perform in the UEFA league group that precedes the knockout phase?
Sentence (from "2017–18 UEFA Champions League knockout phase"): The 2017–18 UEFA Champions League knockout phase will begin on 13 February and end on 26 May 2018 with the final at the NSC Olimpiyskiy Stadium in Kiev, Ukraine, to decide the champions of the 2017–18 UEFA Champions League.
Relevant evidence: Yes