Brooklyn Nets forward Rodions Kurucs allegedly assaulted his live-in girlfriend during a tense domestic dispute, prosecutors and police sources said Tuesday.

The 21-year-old, Latvian-born hoopster answered a misdemeanor assault charge in an afternoon appearance in Brooklyn criminal court, in which he did not enter a plea before he was released without bail.

Amid a heated June 27 argument with his 32-year-old girlfriend inside his Gowanus apartment, Kurucs grabbed a knife and threatened to kill himself, sources said.

But the athlete — who towers at 6-foot-9 and 210 pounds — soon redirected his meltdown toward his partner, dropping the knife to allegedly grab her by the neck, throw her on the bed and slap her, sources said.

The woman — whose name is being withheld by The Post because she is the victim of domestic violence — suffered a left rib injury when she fell off the bed during the dust-up and had to go to an area hospital, officials and sources said.

She reported the alleged spat to police on Aug. 27, and Kurucs turned himself in at the 76th Precinct station house in Brooklyn early Tuesday.

Kurucs, handcuffed and wearing a black hoodie and jeans, was slapped with an order of protection barring him from contacting the woman.

His lawyer claimed that the woman made the allegations after an “unfortunate break up.”

“The former couple flew away together arm in arm in the days that followed,” the laywer Alex Spiro said. “And only after an unfortunate breakup did these claims appear — claims that the misdemeanor hearing revealed were backed by no photographs or objective medical facts.”

Kurucs, who averaged 8.5 points and 3.9 rebounds per game in his debut NBA season last year, is expected to be a key bench piece for the Nets in the upcoming season.

He’s due back in court on Oct. 21 — just two days before the Nets open the 2019-2020 season with a home tilt against the Minnesota Timberwolves.

“After learning of the allegations against Rodions Kurucs, we notified and are assisting the League Office as they begin the process of gathering more information,” said a Nets spokesman. “The Nets organization takes allegations of this nature with extreme seriousness. While the investigation is underway and as we continue to learn more, we will refrain from commenting further.”

Additional reporting by Craig McCarthy