Kim Kardashian and Calvin Harris party with Jennifer Lopez

Taylor Swift's ex-boyfriend Calvin Harris and her adversary Kim Kardashian hung out together in Las Vegas on Saturday (23Jul16) as they attended a birthday bash for Jennifer Lopez.

Both Calvin and Kim have been engaged in social media spats with Taylor in recent weeks, and they turned heads this weekend as they partied together with birthday girl JLo at Caesar's Palace.

"Kim and Calvin did talk and interact, smiling and chatting for awhile," an eyewitness tells UsMagazine.com, although it is unclear what the unlikely pair discussed.

According to TMZ.com, they also posed for a group photo together with Jennifer and rapper French Montana, who also attended the celebration, which took place following Lopez's All I Have residency show at the nearby Planet Hollywood Resort & Casino.

Other guests included music mogul Antonio 'L.A.' Reid, actor John Stamos, singer Tank, soccer icon Cristiano Ronaldo, and Jennifer's boyfriend, dancer Casper Smart, who all sang Happy Birthday to Lopez as she made her big entrance, dressed in a sexy brown jumpsuit with sheer panelling. Kim then presented Jennifer, who actually turned 47 on Sunday (24Jul16), with a large birthday cake.

Kim was in Sin City to host another party at Hakkasan nightclub on Friday (22Jul16), but her trip didn't get off to the best start after she chipped her front tooth and had to undergo emergency medical treatment, a visit she documented on Snapchat.

The reality TV star is a big fan of the social media site, famously using the app to 'expose' Taylor Swift, after she denied having any knowledge about Kanye West's controversial shout out in his song Famous, in which the rapper jokes about sleeping with the singer and calls her a "b**ch".

Kanye subsequently insisted Taylor had given her approval for the lyrics, and on 17 July (16), Kim backed up her husband by sharing a series of videos online, which showed the two musicians discussing the tune on the phone prior to its release in February (16).

Following the footage release, Taylor released a statement insisting she was never told that Kanye was going to refer to her as a "b**ch" in the song, and never gave permission for him to do so.

Meanwhile, Taylor has also fallen out with Calvin after the couple of just over a year split in late May (16). Their relationship hit headlines again earlier this month (Jul16) after Taylor's representatives revealed she was the co-writer of the DJ's hit Rihanna collaboration This Is What You Came For, which she had originally penned using a pseudonym.

Calvin subsequently confirmed her contribution, but then accused the pop star and her team of manipulating the news to make him "look bad", even though Taylor was the one who suggested keeping her involvement under wraps.

The Shake It Off hitmaker quickly moved on from her break-up with Calvin by embarking on a new romance with British actor Tom Hiddleston, while the Scottish dance star has since been linked to R&B singer Tinashe.