The Bavarians burst out of the blocks in what was a virtually flawless display by the defending league champions.
Diaz struck inside the first minute to give them a very early lead and they never looked back.
Harry Kane continued his prolific form in the 27th minute with his 18th Bundesliga goal in just 10 games this season before Diaz wrapped up proceedings with his second of the game in the 84th minute.
Bayern rarely looked in danger of conceding all game in a very impressive performance.
Elsewhere in the Bundesliga on Saturday, Samuel Mbangula's second-minute strike was enough to hand Werder Bremen a 1-0 win over St Pauli, while Yan Couto (23') and Christoph Baumgartner (7') traded goals in the 1-1 draw between Borussia Dortmund and RB Leipzig.
Bayer Leverkusen looked to be getting back to form in their 2-0 win over Union Berlin, with Ernest Poku (33') and Christian Kofane (33') providing the goals.
Augsburg overcame Wolfsburg 3-1 to move out of the relegation zone and above them on the league table.
Noahkai Banks opened the scoring in the third minute before Mert Komur doubled their advantage six minutes into the second half.
Robin Fallhauer added the third in the 63rd minute before Adam Daghim pulled one back for Wolfsburg just two minutes later.
Bayern Munich coach Vincent Kompany has confirmed that young goalkeeper Jonas Urbig will start against Borussia Monchengladbach in the Bundesliga on Saturday, stepping in for Manuel Neuer.
Bayern Munich have made it clear that Michael Olise is not for sale, with sporting director Max Eberl confirming there is no release clause in the French winger's contract despite growing interest from top European clubs.
Seventeen-year-old Lennart Karl produced a memorable performance as Bayern Munich eased to a 4–0 win over Club Brugge in the Champions League.
Arne Slot said Liverpool's dominant 5-1 Champions League victory at Eintracht Frankfurt had been the perfect response to their recent struggles, describing it as "a big, big difference" from their previous performances.
