The pair were seen together at the Corner Tavern alongside a group of friends. "They were there together and were with a couple of other friends," one looker Jahti Anderson told Celebuzz. "They were having a great time. They were definitely acting couple-y."
According to the eye-witness, Liam, 24 and Nina, 25, also shared a kiss before going their separate ways at the end of the night.
"They stayed around two to three hours and Nina left before Liam, and as she was leaving they gave each other a good night kiss… she ran off into a car service with her friend," the eyewitness reported.
"The kisses were on the lips publicly outside of the bar… and it was three sensual kisses on the lips," he confirmed.
The stars are both currently in Atlanta while Nina films Vampire Diaries season five, and Liam finished The Hunger Games: Mockingjay, Parts One and Two.
Liam called off his engagement to Miley Cyrus in September last year, and was most recently linked to Eiza Gonzalez.
Nina, meanwhile, dated her Vampire Diaries co-star Ian Somerhalder between 2010 and 2013, and was spotted on a dinner date with Derek Hough in September.