Carlos Alcaraz marked his return to the world number one spot by comfortably seeing off fellow Spaniard Albert Ramos-Vinolas in his first ever match at the Italian Open on Saturday, as play was cut short by miserable wet weather.
In-form Alcaraz ensured top spot just by taking to the court to play his second round match in Rome as he seeks a third straight tournament win.
The 20-year-old, who saw off Ramos-Vinolas 6-4, 6-1, will overtake Novak Djokovic as world number one and is assured of the top seeding at the French Open later this month.
He came through in a match which started several hours late due to the pelting rain which drenched the Italian capital.
"The conditions here weren't easy, the rain, the waiting all day, not knowing if I was going to play or not. It was tough," said Alcaraz.
He added: "For me it doesn't change too much to be number one or number two seed. I just focus on the tournament and on my game."
The Spaniard became the youngest ever world number one thanks to his US Open triumph last September, with Djokovic denied entry to the United States because of his Covid vaccination status.
Alcaraz will begin his 23rd week at world number one on May 22.
The second seed arrived in the Italian capital on a fine run after back-to-back clay court titles in Barcelona and Madrid, and he made short work of Ramos-Vinolas.
He took control of the match in what turned out to be the final game of the first set, breaking Ramos-Vinolas to take the lead in what had been up to that point a hard-fought match.
From there Alcaraz went through the gears, unleashing a wide repertoire of shots which left Ramos-Vinolas bamboozled and set up a third-round clash with either Jiri Lehecka or Fabian Marozsan.
Fifth-ranked Stefanos Tsitspas was set to join Alcaraz in the third round as he led Portugal's Nuno Borges 6-4, 4-3 when play was halted for the day due to another downpour.
The Italian Tennis Federation said that play would restart at 11am local time (0900 GMT) on Sunday, meaning both Daniil Medvedev and Alexander Zverev were left waiting for their opening matches.
Caroline Garcia became the fourth top 10 player to be dumped out of the women's tournament after the world number four lost 6-4, 6-4 to outsider Camila Osorio.
Qualifier Osorio almost broke down in tears after her shock straight sets victory in a match which started two hours late and was interrupted for more than an hour at the start of the second set.
A career-best win for world number 100 Osorio puts her in the last 16 of a WTA 1000 event for the first time.
She will face Beatriz Haddad Maia in the next round.
"I literally have no words to describe what I'm feeling right now," said Osorio on court.
"I've been struggling a little bit with my injuries and now that I'm back playing and beating the number four in the world I can't believe it.
"I'm just super happy and proud about how I managed to stay calm and finish the match."
Garcia joins world number two Aryna Sabalenka, third-ranked Jessica Pegula and world number seven Ons Jabeur in being dumped out of the tournament.
World number six Andrey Rublev was one of the few lucky ones to escape the early rain, defeating Alex Molcan 6-3, 6-4.