Serving to stay in the set, Nadal committed two backhand errors to drop his serve and the set.
Nadal then left the court briefly with the trainer to have his then unknown chest injury treated.
In set two Fritz continued his strategy of striking many powerful crosscourt forehands to the Nadal backhand. Nadal attempted to change the pace with many one handed crosscourt slice backhands in addition to his normal two handed topspin backhand.
However Nadal was drawn into several backhand errors. Fritz held serve to lead 5-4 after Nadal struck two crosscourt backhands long.
With Nadal serving to stay in the match, Fritz struck an inside out crosscourt forehand winner which he followed up with a down the line forehand winner to reach matchpoint.
However the American struck two baseline errors before Nadal hit a down the line forehand winner to hold serve and level the set at five games all.
Both players then held their following service games to reach the second set tiebreaker.
Fritz struck a powerful inside out down the line forehand winner to lead 2-0.
At 4 all in the tiebreaker, Nadal hit an overhead winner to lead 5-4 before sending a swing crosscourt inside out forehand volley wide to level the score at 5 all.
Nadal sent a crosscourt forehand wide to trail 5-6 and face a second matchpoint.
Fritz then struck a powerful down the line forehand which Nadal framed in a forehand on the run to end the match.
After shaking Nadal's hand at the net, Fritz made his way to his box in the stands to hug his team.
Nadal finished the day with 34 unforced errors.
Fritz struck 20 winners for the day while saving 8 of 10 breakpoints.
And by winning the Indian Wells singles' title, Taylor Fritz overtakes Reilly Opelka to become the highest ranked American male tennis player at number thirteen.