Novak Djokovic suffered his third straight defeat as Dutch lucky loser Botic van de Zandschulp pulled off a shock victory in the second round at Indian Wells.
The seventh seed lost 6-2 3-6 6-1 to the world number 85 in a subdued performance.
Since memorably beating Carlos Alcaraz in the Australian Open quarter-finals, the 37-year-old has lost to Alexander Zverev in the semi-finals in Melbourne, Matteo Berrettini in Doha and now Van de Zandschulp.
The 24-time Grand Slam champion won only one title last year – albeit the elusive Olympic gold he had always coveted – and failed to win a major for the first time since 2017.
“Things are obviously different for me in the last couple of years. I’ve been struggling to play on the desired level,” said the Serb.
“Every now and then, I have couple good tournaments, but mostly it’s really a challenge. It’s a struggle for me.”
Meanwhile, Spanish second seed Alcaraz started his defence of the men’s title with a routine 6-4 6-2 win against French opponent Quentin Halys.
