LEN decided to play the 10 match-days of the 2020–21 LEN Champions League preliminary round in bubble format in three rounds, using two venues at each occasion. The ten match-days will be played in three rounds at two venues each time. Teams of the same group will contest three match-days, one time four, where the participants will be isolated for the entire duration of event because of the COVID-19 pandemic.
The draw for the group phase took place in Rome on 19 October 2020.