The 2017–18 LEN Champions League was the 55th edition of LEN's premier competition for men's water polo clubs.
Overview
Team allocation
12 teams are directly qualified for the preliminary round (TH: Champions League title holders).
Phases and rounds dates
The schedule of the competition is as follows.
Qualifying rounds
Qualification round I
Group A
Group B
Group C
Qualification round II
Group E
Group F
Group G
Group H
Qualification round III
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Preliminary round
The draw for the group stage was held on 29 August 2017 in Budapest. The 16 teams were drawn into two groups of eight.
In each group, teams play against each other home-and-away in a round-robin format. The group winners, runners-ups, third and fourth placed teams advance to the Final 8. The matchdays are 25 October, 8 and 29 November, 9 and 20 December 2017, 13 and 24 January, 7 and 28 February, 14 and 31 March, 18 and 28 April, 9 May 2018.
A total of 11 national associations are represented in the group stage.