ROME -- Novak Djokovic knows it isn't model behavior when he loses his cool on the tennis court.
Yet he just can't help himself.
Exactly two weeks after he was defaulted from the US Open, and a day after he was warned by the chair umpire for breaking his racket, Djokovic received an obscenity warning midway through a 7-5, 6-3 win over Casper Ruud in the Italian Open semifinals Sunday.
As opposed to his previous two outbursts, this time there were fans in the stands who could clearly hear how Djokovic dealt with his frustration.
What's more is that, with 1,000 spectators allowed in to the Foro Italico for the first time this week, a large proportion of those in attendance were children.
"I don't want to do it, but when it comes, it happens," Djokovic said Saturday. "That's how I, I guess, release sometimes my anger. And it's definitely not the best message out there, especially for the young tennis players looking at me. I don't encourage that -- definitely."
Djokovic's behavior once again overshadowed his performance, in a match where he had to save two set points when Ruud served for the first set at 5-4 -- one of them with a delicate backhand drop-shot winner.
The top-ranked Djokovic also served five aces in a single game to take a 6-5 lead in the first.
Ruud, 21, the first Norwegian player to contest a Masters 1000 semifinal and a product of Rafael Nadal's academy, put up plenty of resistance and also produced the shot of the day: a leaping over-the-shoulder hook shot for a winner as he raced back to chase down a lob -- earning a thumbs-up from Djokovic.
The obscenity warning came in the third game of the second set, by which time he had a running dialogue with the chair umpire over a series of contested calls.
Still, Djokovic improved to 30-1 this year. His only loss came when he was thrown out of the US Open for unintentionally hitting a line judge in the throat with a ball during his fourth-round match against Pablo Carreno Busta.
In Djokovic's 10th Rome final -- he has won four -- he'll face either eighth-seeded Diego Schwartzman or 12th-seeded Denis Shapovalov.
Schwartzman beat nine-time Rome champion Nadal late Friday.
In the women's tournament, top-seeded Simona Halep reached her third Rome final by beating Garbine Muguruza 6-3, 4-6, 6-4 to improve her record in tennis' restart to 9-0.
Muguruza struggled with her serve and double faulted on the final two points of the 2 hour, 16-minute match.
Halep, who lost to Elina Svitolina in the 2017 and 2018 finals, will face either Karolina Pliskova or Marketa Vondrousova in Monday's championship match.
The second-ranked Halep is 13-0 overall stretching back to February, when she won a title in Dubai. After the tour's five-month break due to the coronavirus pandemic, the Romanian returned by raising another trophy in Prague last month. She then skipped the US Open due to travel and health concerns.