Novak Djokovic rued a "horrible" performance as he crashed out of the Monte Carlo Masters in his opening match on Wednesday, while Carlos Alcaraz staged a fightback for his first win at the tournament.

The fifth-ranked Djokovic struggled to find his rhythm in a 6-3, 6-4 loss to Chilean Alejandro Tabilo in the second round, making an inauspicious start to his clay season.

Djokovic, 37, went into the tournament hampered by an eye infection that has been troubling him since the semi-finals in Miami at the end of March and admitting that he did not have "very high" expectations for Monte Carlo.

As it transpired a sluggish performance meant that Tabilo, who also beat Djokovic on clay in last year's Italian Open in Rome, faced few difficulties in claiming a rare 2-0 head-to-head record against the 24-time Grand Slam winner.

"It was actually more like the worst day (at the office)," said Djokovic. "I was hoping it was not going to happen, but it was quite a high probability I'm going to play this way.

"Just horrible. Horrible feeling to play this way, and just sorry for all the people that have to witness this."

The Serb, who is chasing his 100th ATP title, has not won a tournament since taking gold at last year's Paris Olympics.

Djokovic brushed off any fitness concerns and said his main focus for the clay season was the French Open. He is set to play in Madrid later this month for the first time since 2022.

"I expected myself at least to have put a decent performance. Not like this. It was horrible," said Djokovic, who has only once reached the semi-finals in Monte Carlo since the last of his two titles in the principality in 2015.

"I did not have high expectations, really. I knew I'm gonna have a tough opponent and I knew I'm gonna probably play pretty bad. But this bad, I didn't expect."

Tabilo, ranked 32 in the world, will face Bulgarian Grigor Dimitrov in the last 16.

"It has been a tough year, so a little bit of the nerves were there," said Tabilo, who earned consecutive tour-level wins for the first time since August. "It was an unreal match."

- Alcaraz 'aggression' -

Alcaraz, meanwhile, picked up his first ever Monte Carlo win when he came from a set down to win his second round match against Francisco Cerundolo 3-6, 6-0, 6-1.

After a mixed American tour, with a semi-final in Indian Wells and an early loss to David Goffin in Miami, the 21-year-old Spaniard made a successful return to clay.

His only previous appearance in Monte Carlo in 2022 ended in a three-set defeat by Sebastian Korda.

Alcaraz, ranked three in the world, made a slow start against the lively Argentinian who outlasted him in extended cross-court rallies.

After gaining an early break, Alcaraz gave up four games in a row which was enough for Cerundolo to go on and take the set.

From then on, however, it was all Alcaraz. He dropped just a single game over the next two sets as he blasted his way to victory in one hour and 38 minutes.

"I didn't start well," said Alcaraz.

"I made a lot of mistakes and I let him play inside the court, dominating the points.

"I just knew that I had to do something else, play more aggressively, and play my own tennis: drop shots, going to the net and show more aggression.

"The most important change was the return, I tried to return closer to the line and push him."

The second seed booked himself a last 16 date against the German Daniel Altmaier, 84th in the world, who saw off the French veteran Richard Gasquet 7-5, 5-7, 6-2.

Gasquet, 38, playing for the last time in Monte Carlo, was given a warm reception by the crowds who have been watching him since he made his tournament debut as a 15-year-old wild card in 2002.

"I started with (Andre) Agassi and I'll finish with Alcaraz," said Gasquet who will retire from the circuit after the French Open.

"It's a gap of almost 40 years, it's enormous."

Fourth seed Casper Ruud, last year's runner-up, swept past Roberto Bautista Agut 6-2, 6-1, while 2023 champion Andrey Rublev beat Gael Monfils in straight sets.

Daniil Medvedev, Alex de Minaur, Arthur Fils and Lorenzo Musetti also advanced among the seeds.