Valencia vs Monaco is already playing.
I'll be watching The Famous Arsenal vs Benfica in the Emirates Cup. Also, Real Madrid - which will draw a record crowd for an American audience at a football match.
Here are other key matches today (this is not a reflection of the times they are played. Schedule in your time zone can be found at ifirstrow.eu - a great place for streams).
Liverpool vs AC Milan
Cardiff vs Wolfsburg
Toronto FC vs Montreal Impact
Manchester United vs Real Madrid
Nice vs Barcelona
LA Galaxy vs Timbers
Olympiacos Pireus vs Manchester City
Fenerbahce vs Sevilla
Inter Milan vs Roma
Schalke vs West Ham
Tottenham Hotspur vs Celtic