Novak Djokovic says he is facing up to a "new reality" after losing his opening match for the second successive tournament.

The Serb, seeking a fourth Madrid Open title, was beaten 6-3 6-4 by Italian Matteo Arnaldi.

Djokovic made his Madrid debut in 2006 and won the tournament in 2011, 2016 and 2019.

However, he said does not yet know if he will play again in Madrid following Saturday's loss to a player ranked 44 in the world.

When asked if it was his final match there, he said: "I'm not sure if I will come back. So, I don't know.

"I mean, I'll come back, maybe not as a player. I hope it's not, but it could be."

Djokovic said his "level of tennis is not where I would like it to be", and added: "I lost to a better player.

"I've had a few of these this year where I lose in the first round, unfortunately."

It was a third consecutive defeat for the 24-time Grand Slam winner, who is seeking a 100th career title.

He also lost in his opening match in Monte Carlo this month, after being beaten in the Miami Masters final in March.

"[It's a] kind of new reality for me, I have to say," he said.

"You know, trying to win a match or two, not really thinking about getting far in the tournament.

"It's a completely different feeling from what I had in 20-plus years of professional tennis, so it's kind of a challenge for me mentally to really face these kind of sensations on the court, going out early now regularly in the tournaments.

"But that's, I guess, the circle of life and the career. Eventually it was going to happen."