World number one Novak Djokovic flew past Roman Safiullin in straight sets at the Monte Carlo Masters on Tuesday, after third seed Carlos Alcaraz announced his withdrawal from the event due to injury.
After receiving a bye in the first round, Djokovic was imperious on the main Rainier III court as he won 6-1, 6-2 against the unseeded Russian.
"I am very pleased... I think even the games that I lost I had break points in those games. It is a great first match at the start of the clay season," said Djokovic.
The Serb needed just one hour and 10 minutes to make a return to winning ways in his first match since a shock early exit at Indian Wells to Italian Luca Nardi.
The 36-year-old became the oldest world no.1 in the history of the ATP rankings when he took to the court in Monte Carlo, surpassing Roger Federer's record.
"It is nice, it is great," said the 24-time Grand Slam winner.
"I met (Rohan) Bopanna yesterday, who is the oldest doubles no.1 in history. He said we had a combined age of 80, but he does contribute to the 80 more than I do. But it is fun."
But there was no sign of Djokovic feeling his age as he broke Safiullin's serve twice to race into a 4-0 lead in the first set.
Djokovic went on to break his opponent's serve five times throughout a routine win and now faces a third-round meeting with either Lorenzo Musetti or rising French starlet Arthur Fils.
Before Djokovic took to court, Alcaraz announced he was pulling out of Monte Carlo after failing to recover from an injury to his right forearm.
"I have been working in Monte Carlo and trying to recover until the last minute from an injured pronator teres (muscle) in my right arm, but it was not possible and I cannot play," Alcaraz wrote on social media.
The 20-year-old Spaniard, whose last match came in the straight sets defeat by Grigor Dimitrov in Miami last month, was due to go straight into Wednesday's second round in Monte Carlo against Canadian Felix Auger-Aliassime.
He will be replaced in the draw by Italian Lorenzo Sonego, who was drafted in as a lucky loser, the ATP announced.
The match against Auger-Aliassime was set to be the two-time Grand Slam winner's second-ever appearance at Monte Carlo, following his withdrawal from the tournament last year and a three-set defeat in his only match of the 2022 edition.
Earlier in the day, American Sebastian Korda, the man responsible for that defeat in 2022, stormed past Alejandro Davidovich Fokina 6-1, 6-2 in the first round.
De Minaur dismisses Wawrinka
After a rain-hit morning causing a two-and-a-half-hour delay to the day's play, world no.11 Alex de Minaur made up for lost time with a 62-minute straight sets win over Stan Wawrinka.
The 39-year-old wild card Wawrinka formerly ranked no.3 in the world but now down to no.79, was no match in the first round for the Australian who prevailed 6-3, 6-0.
Wawrinka, the 2014 champion in Monte Carlo and a three-time Grand Slam winner, made 28 unforced errors to De Minaur's 18 and landed just four winners to the 12 made by his opponent.
In the next round, De Minaur, who won this year's title on the hard courts in Acapulco, will face Dutchman Tallon Griekspoor.
Spaniard Roberto Bautista Agut beat lucky loser Facundo Diaz Acosta 6-2, 6-4, while China's Zhang Zhizhen won in three sets against Marcos Giron of the United States.
The 10th seed Hubert Hurkacz overcame Britain's Jack Draper after nearly two and a half hours on court to reach the second round, winning 6-4, 3-6, 7-6 (7/2).
After winning a first title in two injury-hit years in Marrakesh on Sunday, Italian Matteo Berrettini's run in Monte Carlo was cut short by Miomir Kecmanovic 6-3, 6-1.