She was one of the biggest names to grace the stage at the annual Capital FM Summertime Ball on Saturday.But it wasn’t only Ariana Grande’s sexy stage costume wasn’t the only aspect of her appearance which raised eyebrows.The singer, who arrived later than most of her the other performers, risked a backstage run-in with two famous men in her life, both past and present.Scroll down for videoPop princess: Ariana Grande brought her own style of raunchy pop to the Capital FM Summertime ball in London on SaturdayThe concert’s line-up included former The Wanted star Nathan Sykes, who dated Ariana in 2013, and One Direction’s Niall Horan, who was linked to the Boom Boom hitmaker just this week.Both Nathan and Niall were billed to take to the stage before the singer, narrowly missing a run-in on the red carpet.While her intense four-month romance with Nathan fizzled out some while ago, Ariana, 21, addressed rumours of a romance with Irish heartthrob Niall on her way into the event.Skirting around the question of whether the pair were dating, she told the Mirror: ‘Well, that’s just society. She must be pregnant, she must be expecting twins! But he’s really nice.Awkward: The singer risked run ins with men past and present in her life at the concert; she dated Nathan Sykes in 2013 and was linked to One Direction star Niall Horan just this week‘He’s nice’: The singer, 21, avoided questions on whether she was dating the Irish heartthrob before her racy performance, insisting she had a fun night out with him in London this weekBack to the music: Ariana showed off her petite figure in a daring leotard and knee high bootsWork it: Ariana had the crowd eating out of her hand as she strutted her stuff in front of thousands of revellersWell heeled: Ariana gave herself a boost in the height stakes with a killer pair of crystal-encrusted stiletto bootsSing it: She may be small but the star proved she can certainly sing as she belted hit after hit‘I’m honestly so tired of talking about dating and my love life and everything.’The duo was first linked when Ariana was seen leaving Niall’s Hertfordshire mansion last week after a night out in London.Niall – who recently split from Australian student Melissa Whitelawwas – was also spotted visiting her at a central London hotel just hours later.

Talking about their rendezvous, Ariana insisted it was all innocent fun, adding: ‘My friend Fredo is really close with Niall and he came to my show in London, I met him there, he was super nice.Going solo: Nathan, who dated Ariana for an ‘intense’ four months in 2013, went out on his own following his band The Wanted’s split last yearRed-dy to go: The star ensured he wouldn’t be missed in a very bright ensembleBack in town: Niall provided guitar for One Direction’s songs as the band took to the stage for their first London show as a foursome following Zayn Malik’s departure in MarchStaying together: The boys insisted reports they were set to split were false, with Liam Payne (centre right) saying ‘I don’t think we are going anywhere for a while’‘We then all went over [to Niall’s] for a game night, it was really fun.’Meanwhile, Ariana soon ensured the attention was off her love life and back on her when she hit the stage.The pint-sized performer sexed up the annual concert by belting out her hits in a very revealing leotard, which showed off her lithe legs.She wore her hair up in her signature high ponytail, with a pair of Monica Vinader earrings.Her performance came after Niall and his bandmates Harry Styles, Liam Payne and Louis Tomlinson rocked out in London for the first time since Zayn Malik’s departure in March.They took the opportunity in person to shrug off reports they were heading for a split.Liam said: ‘We have just started the process for recording the new album, we’ve got a whole new tour going on, there are some really good songs so I don’t think we are going anywhere for a while.’Double date: Niall was spotted visiting Ariana at her London hotel this week, just hours after she left his Hertfordshire mansion in the early hours of the morning