Another great part of Lee’s career was his rivalry with Gu Li, which reached its pinnacle in a jubango (10-game challenge match) in 2014.
It was a real joy following this jubango through GoGameGuru’s coverage. Although GoGameGuru is now unfortunately defunct (and its domain name has been taken over by a spammer), I was able to find the old coverage archived on the Internet Archive Wayback Machine:
This page contains working links to other archived pages, two for each game (one to announce the result and a second to provide more detailed commentary). The videos were behind a paywall (BadukTV), so those are not archived and probably not available anymore.
The people behind GoGameGuru also published a book that thoroughly analyzes the jubango as well as covering the other games between Lee Sedol and Gu Li: https://senseis.xmp.net/?Relentless
Edited to add: there is also this YouTube video that they released to promote the jubango