Federer continued: "I wasn't playing that good in my first [opening] round".
"The rest, I said I will decide after Miami to then decide what I will play if I do play the clay court after that". After another 90-minute delay organisers suspended play for the night.
He extended his 2018 win streak to 13 matches and has only dropped three sets from 34 played this year.
Another Spaniard, 28-ranked Feliciano Lopez, also won his match against the American Ernesto Escobedo 6-4, 6-3.
While Federer was far from ideal, he did improve to an unblemished 13-0 on the year and took the next step in snaring his third title of the young season.
Federer and 10th seed Djokovic both came into the tournament seeking to become the first six-time victor of the event.
Daniel, who beat Britain's Cameron Norrie in the first round, will next meet Leonardo Mayer, who defeated Ruben Bemelmans 6-4 6-1.
Speaking to the media after the match, Djokovic said, "It felt like my first match on tour".
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Venus did her part to set up the marquee match when she dismantled World No.35 Sorana Cirstea 6-3, 6-4 in just 79 minutes. Still showing some rust from her long layoff, Serena hit just one ace and made 37 unforced errors to 32 for Bertens.
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"Very weird. I mean, I just completely lost rhythm, everything".
Djokovic shut down his season after Wimbledon in 2017 and despite not being at his best, made a decision to play at this year's Australian Open where he was ousted by South Korea's Hyeon Chung in the fourth round.
Djokovic had four aces but served poorly overall, making four double faults.
It was clear early that Djokovic didn't have anything close to his best game, in spite of holding a 5-2 lead in the first set.
Retaining the world No. 1 ranking is the furthest thing from Roger Federer's mind as he bids to defend his Indian Wells crown. "When you go away from the game for over a two-month period, it starts feeling a little bit that way". When you do come back from injury or when you haven't played in a long time, it just takes extra effort.
The 30-year-old, who was involved in a two-way battle with Andy Murray for the year-ending world no. 1 spot in 2016, was forced to cut short his 2017 season due to persistent issues in his racket-swinging arm.
The top seed fended off a set point in the tiebreak to beat Delbonis 6-3 7-6 (6).