Sinner eases into Italian Open last 16, Osaka dumped out
World number one Sinner continued his Foro Italico comeback from a three-month doping ban by dealing with De Jong and setting up a clash with Argentina's Francisco Cerundolo in the next round.
Sinner was knocked out in the last 16 by Cerundolo the last time he played here, in 2023, and he is under no illusions that the 17th seed will be a big step up after two low-ranked opponents.
"Let's see, he's an amazing player, he has an amazing season until now," said Sinner of Cerundolo.
"It's going to be tough. For sure I have to raise my level... It's going to be a good challenge, a good test for me and we'll see how it goes."
The over 10,000 fans crammed into the centre court stands hope Sinner can end a 49-year wait for an Italian winner of the men's tournament in the Italian capital.
But Monday's win was in reality another warm-up for 23-year-old's stated objective of arriving at the French Open in top form.
De Jong, ranked at a career-high 93rd in the world, offered some resistance in a low-key contest in which Sinner showed signs of rustiness.
Sinner threw away a three-game lead when 4-1 up in the first set before eventually going ahead in the match but he saw out the contest with little fuss, helped in part by De Jong hurting his wrist in a fall in the fourth game of the second set.
Sinner's compatriot Jasmine Paolini cruised past Jelena Ostapenko and into the women's quarter-finals, easing past her Latvian opponent in straight sets 7-5, 6-2.
Sixth seed Paolini will face Diana Shnaider in the last eight as she eyes another deep run in a 1000 series tournament after losing to world number one Aryna Sabalenka, who later takes on Marta Kostyuk, in the Miami semi-finals.
Matteo Berrettini will follow Sinner in a tough clash with sixth seed Casper Ruud, as fans hope for a hat-trick of wins on centre court for their local heroes.
Osaka out
Naomi Osaka's struggle for form at the top level continued with her 6-4, 3-6, 7-6 (7/4) defeat to Peyton Stearns.
In the quarter-finals Stearns will face Elina Svitolina, a 6-4, 6-2 winner over Danielle Collins, after coming through an attritional match which lasted the best part of three hours on a baking centre court.
Osaka is another big name that American Stearns has beaten in Rome after also knocking out fifth seed Madison Keys in the previous round.
Former world number one Osaka has looked a long way from the player who won four Grand Slams.
She returned last year from a 15-month break from tennis for the birth of her daughter.
Her comeback was also hampered by an abdominal injury that forced her out of the Australian Open, after which early exits at Indian Wells and Madrid highlighted how far she was from her best.
Osaka warmed up for Rome by winning a minor event in Saint Malo in France earlier this month.
But she has failed to get past the last 16 of a tournament higher than the WTA 125 series since losing the Auckland final back in January.
Coco Gauff made short work of Britain's Emma Raducanu, winning 6-1, 6-2 in just over an hour to reach the last eight where one of Mirra Andreeva or Clara Tauson awaits.