Despite Jennifer Lopez's claims that she is not dating reigning "Dancing with the Stars" professional dancer champion Maksim Chmerkovskiy, the two were reportedly quite close at her 45th birthday party on Thursday at Nammos Greek restaurant and lounge in Southampton, New York.

An Us Weekly source said that Chmerkovskiy arrived at the party late because he was rehearsing for an event at Sway. Still, he made it a point to attend as Lopez reportedly invited him "personally," the tabloid magazine reports. Perez Hilton reports that the "Dancing with the Stars" champion arrived at the Hamptons spot shortly after 1 a.m.

"They seemed really happy to see each other," a Perez Hilton "eyewitness" said.

According to the source, the two were being affectionate toward one another. The Us Weekly source agreed.

"[Lopez and Chmerkovskiy were] a very cute couple hanging with Scott [Disick] all night," another Us Weekly source claimed.

Other party attendees included fellow Bronx natives Fat Joe and French Montana, as well as Khloé Kardashian, Russell Simmons, Kristen Chenoweth and Benny Medina, who reportedly gave a "very heartwarming speech" about the Latina diva.

"It's not the years we live in life, but what we make of it," he said. 

Lopez's best friend Leah Remini also attended.

"Jennifer was dancing with Leah Remini for a while and smiling and greeting everybody," an Us Weekly source said.

The party reportedly ended at 4 a.m.

In June, Lopez denied that she was dating Chmerkovskiy, 34.

"@Qburgh No I'm not. #rumors #nottrue #AKAinstoresJune17 :)," she said via Twitter after Pittsburgh radio station Qburgh tweeted the rumor. "... No I'm not. (dating anyone new already.)"

The "Dancing with the Stars" winner has neither confirmed nor denied the rumors, as it goes against his policy.

"You're not gonna get an answer you're looking for no matter who you are and who's reporting," Chmerkovskiy told Access Hollywood last month. "I just don't think that it's anybody's business."
--- 

Follow Scharon Harding on Twitter: @ScharHar.