Novak Djokovic made no excuses for the poor performance that sent the five-time Indian Wells champion packing from the California desert on Saturday after falling 6-2 3-6 6-1 to Botic van de Zandschulp in the second round.

Djokovic, 37, retired from his Australian Open semi-final against Alexander Zverev with a hamstring injury but his movement did not appear hampered on a sun-soaked day on Stadium One court.

"Obviously no excuses for a poor performance," he told reporters.

"It doesn't feel great when you play this way on the court, but congratulations to my opponent. Just a bad day in the office, I guess, for me.

"I regret the level of tennis considering how I practice these days."

The Serbian great came out flat against the tournament lucky loser, who took full advantage of a blizzard of errors from the 24-time Grand Slam champion to capture the first set.

Djokovic raised his level to grab the second but van de Zandschulp refused to back down, running away with the decider before the sold-out crowd.

The Indian Wells courts have been resurfaced this year to make them more in line with the conditions at the Miami Open and U.S. Open and Djokovic said he struggled to read the bounce of the ball.

"The difference between the centre court and the other courts is immense," he said.

"The ball is bouncing on the centre court higher than some of the highest clay courts, to be honest. Just struggled a lot with that. Couldn't find the rhythm."

Djokovic said he would need to speak to rival-turned-coach Andy Murray before deciding next steps. Prior to his first match he said he would play the second leg of the "Sunshine Double" at the upcoming Miami Open.

"Still haven't talked with Andy and the team, so going to do that and make a plan," he said.

After his withdrawal from Australia, his loss in the opening match at Qatar Open and his stunning defeat to the Dutchman on Saturday, Djokovic is now on a three match losing streak.

"Things are different obviously for me the last couple of years," he said.

"I've been struggling to play on the desired level. Every now and then I have couple good tournaments but mostly it's really a challenge.

"So it is what it is. I guess nothing can prepare you for that moment, in a sense. You have to experience it and try to deal with it in the best possible way."

- Alcaraz relaxed and ready -

With Zverev out and world number one Jannik Sinner serving a three-month drugs ban, world number three Alcaraz is the highest seed left in the men's draw.

Alcaraz, trying to join Djokovic and Roger Federer as the only men to win three straight Indian Wells titles, eased into his defence with a 6-4, 6-2 victory over France's Quentin Halys.

He admitted he was feeling some nerves to start the match, but they evaporated amid a strong all-around performance.

One early break staked Alcaraz to the first set, and he roared to a 4-0 lead in the second behind a formidable service display.

He finished with seven aces and saved the only break point he faced, securing the win in 67 minutes.

"I was nervous at the beginning of the match," he told a supportive crowd. "The first match is never easy so I was trying to be focused on my game.

"I just tried to be relaxed, as relaxed as I can. Can always be better, but I'm ready for the (next) round and excited."

Australian Open champion Madison Keys opened the day's action in the combined ATP Masters and WTA 1000 event, subduing hard-hitting Russian Anastasia Potapova 6-3, 6-0 in her first match since her maiden Grand Slam triumph.

She showed no sign of rust as she dispatched Potapova in 63 minutes.

Later world number one Aryna Sabalenka launched her bid for an elusive Indian Wells title against hard-hitting American McCartney Kessler.

In other early matches, Americans Taylor Fritz and Coco Gauff both advanced.

Fritz, the 2022 men's champion, defeated Italian qualifier Matteo Gigante 7-5, 6-3 while Gauff -- like Fritz seeded third in her draw -- clawed out a 6-3, 3-6, 7-6 (7/4) victory over Japan's Moyuka Uchijima.