The violence erupted just before 4 a.m. outside 1Oak Club, a trendy Chelsea spot where celebs such as Justin Bieber and Snoop Dogg mingle with partygoers, police said.
The couple was arguing on the street as the attacker eavesdropped and started to interfere, according to police. The dispute escalated until the 22-year-old suspect pulled out a knife and started slashing, police said. Copeland's driver grabbed the suspect and held him until officers arrived.
The suspect, Shezoy Bleary, was in custody, authorities said. Police said charges were pending, and it wasn't clear whether Bleary had an attorney who could comment on them.
Copeland, 31, a former member of the New York Knicks, was stabbed in the left elbow and abdomen and Katrine Saltara was slashed in the arm and across the breast. The second woman, who was believed to be with the attacker, was slashed in the abdomen. The victims were hospitalized and in stable condition, police said. Police recovered a switchblade at the scene.
Pacers coach Frank Vogel said Copeland had surgery on his elbow and abdomen and would be hospitalized overnight. He added it wasn't known yet if Copeland would miss the remainder of the season.
Hawks players Pero Antic, 33, and Thabo Sefolosha, 30, who were not with Copeland but were also at the club, were arrested after police said they blocked officers from trying to start their investigation. The teammates were in town to play the Brooklyn Nets on Wednesday night. The team arrived late Tuesday, after beating the Phoenix Suns in Atlanta.
Antic and Sefolosha were released without bail after a brief court appearance where they were charged with obstructing governmental authority and disorderly conduct. Their attorney, Alex Spiro, said they did not commit any crime.
"They should not have been arrested. We fully expect the case to be dismissed," he said.
The Hawks said neither Antic nor Sefolosha would play against the Nets. Sefolosha was limping during his court appearance and Spiro said he had been injured during the arrest. Coach Mike Budenholzer said the reserve would have his ankle checked.
The players issued a joint statement through the team, apologizing for any embarrassment they caused. The arrests were an unwanted distraction for a team that is less than two weeks away from starting the post-season.
"As members of the Atlanta Hawks, we hold ourselves to a high standard and take our roles as professionals very seriously," the statement said. "We will contest these charges and look forward to communicating the facts of the situation at the appropriate time."
Budenholzer called the incident "unfortunate," but said the Hawks would support Antic and Sefolosha, who remained in New York.
"We're very supportive of our players, and you never want to put yourself in a position where you can bring negativity to yourself or the organization or your teammates, but they're great guys and I think right now it's most important to support them," he said.
The Pacers were in town to play the Knicks; Copeland played with New York during the 2012-13 season. Pacers President of Basketball Operations Larry Bird said the team was aware that Copeland had been injured.
"We are still gathering information and will update when we know more. Our thoughts are with Chris and those injured," Bird said.
Copeland has played infrequently, missing 21 games since Jan. 31. With All-Star Paul George making his season debut Sunday, Copeland's already limited minutes were expected to get cut. Police initially said Saltara was his wife, but Copeland's agent said the two were not married. According to Saltara's Facebook page, they have been engaged for several months.
In a statement, the club disputed the police account. It said the altercation stemmed from a dispute at a public housing project about two blocks away from the nightspot and that Copeland's driver grabbed the suspect, who was later arrested.
"The incident occurred beyond the view of our security. Once alerted, the venue provided all assistance possible," the statement read.
The club did not say how Copeland got back to the front of the club on West 17th Street, where the street was splattered with blood from the altercation.
The nightclub had been cited at least 10 times for altercations and four times for noise in 2014, according to data obtained by the New York Post from the State Liquor Authority.
Associated Press writers Jeff Martin in Atlanta and Rick Callahan in Indianapolis and AP Basketball Writer Brian Mahoney in New York contributed to this report.