One Direction

Ariana Grande and Niall Horan hung out way past their bedtime Monday night -- but don't get your panties in a bunch just yet 1Ders.

Our Ariana sources say the One Direction singer was invited to her concert in London Monday night. After the performance, she and Niall hung out backstage, but it was anything but intimate. Ariana's manager Scooter Braun and both of their entourages were also there.

After the backstage pow-wow, the group headed off to Cirque Le Soir nightclub -- and stayed out till 3:30 AM. But when the fun was over ... we're told they went their separate ways.

Too bad it wasn't a real hook-up since the normally rabid 1D fans have actually been pretty positive about Ariana. Must be the wild video of their after-party that won 'em over.

Harry Styles paid tribute to 1D, as in ... DEEZ NUTS ... in Las Vegas.

One Direction won the Billboard Music Award for Top Duo/Group, and Harry celebrated by slyly grabbing a hold -- playfully and gently, we hope -- of bandmate Niall Horan's balls.

Watch ... Niall plays it off pretty good.

One Direction is ripping a page out of the Justin Bieber playbook ... shedding the whole teen heartthrob thing for Snoop and his mega-blunt.

Louis Tomlinson and Liam Payne got down at Snoop's "Bush" album release party Monday night with the likes of Bow Wow, Bishop Don "Magic" Juan, Slink Johnson, Red Grant, Kurupt and Jermaine Dupri.

Zayn Malik may have actually saved the group from becoming another 98 Degrees, because they now have to recast their image or fade away.

Smoking a blunt with Snoop is a good start.

Liam Payne and Louis Tomlinson got a couple of fabulous parting gifts Friday night from an L.A. club ... 2 more than agreeable chicks.

Two of the remaining members of One Direction were leaving Project L.A. when their bodyguards tried a feeble diversionary tactic ... Liam, Louis and the 2 women all left the club separately, but their cover was clearly blown because they all ended up in the same car.

Zayn Malik's exit from One Direction apparently wasn't as friendly as they wanted us to believe ... because Zayn and Louis Tomlinson are publicly trash talking each other.

Zayn just posted this heavily-filtered photo of himself with record producer Naughty Boy. Louis jumped on it, tweeting, "Remember when you were 12 and you used to think those Mac filters for your picture were cool haha! Some people still do HA!"

Zayn was locked and loaded, firing back, "Remember when you had a life and stopped making bitchy comments about mine?"

People connected with 1D were insisting to us when Zayn left ... everyone was cool about his departure ... which made no sense.

Harry ... your move.

There is nothing in Harry Styles' life that isn't awesome -- super popular band, chicks throwing themselves at him, and tons of money to buy cool classic cars.

The One Direction heartthrob was out Monday in Beverly Hills, crusising in a white vintage Mercedes-Benz SL convertible.

One Direction's Louis Tomlinson is easing back into bachelorhood ... by hooking up with multiple chicks at once -- or so it seemed when a pack of at least 3 went to his London hotel room.

Tomlinson was partying at Cirque Le Soir Wednesday night ... before the after-party moved to the Soho Hotel. Best part of the rendezvous -- the girls' walk of shame Thursday morning -- although maybe it's more like walk of fame ... when you've raged with a One Direction singer all night?

Tomlinson broke up with GF Eleanor Calder last month after 4 years together.

Everyone mourns in their own way.

Harry Styles is about to go the way of Zayn Malik -- bolting from the ranks of One Direction ... at least according to acclaimed director and honorary 1Der Morgan Spurlock.

Spurlock directed the docufilm "One Direction: This Is Us" -- which, outside of Simon Cowell, makes him the foremost expert on the band ... among grown men. Morgan told our photog the band will be fine as a foursome for now, but it's only a matter of time before Harry splits.

But even that won't kill the band. Check out Morgan's prediction for Niall, Louis and Liam.

Think flattops -- on white guys. It just might work ...

Zayn Malik broke his silence Friday night -- come to think about it we haven't heard him speak before -- and he heaped praise on his former band, One Direction.

Zayn accepted a trophy at the Asian Awards in London. The award was for Outstanding Achievement in Music. Interesting, because it's the only award Zayn can accept independent of the band. He's getting it because of his Pakistani heritage.

It sounds like there's no beef with the boys.

Zayn Malik has one direction in mind these days ... South, as in the South of France.

The former "One Direction" singer was leaving a hotel with his fiancee Perrie Edwards Friday.

Zayn wants to repair his relationship with Perrie and spend time with his family, which is why he says he left the group.

The South of France is a good place to win just about anyone over.

Four is the magic number for One Direction, because the band has no plans to add a fifth member following the Earth-shattering departure of Zayn Malik.

Sources close to Simon Cowell and the record label tell TMZ ... the band is moving forward with recording their new album sans Malik. As for eventually finding a replacement -- we're told there's "absolutely zero" talk of that.

That being said ... we're told the remaining 1Ders are still talking to Zayn regularly, and the band completely respects his decision to bolt.

One Direction played its first Zayn-less show in South Africa earlier this week. They tour Europe in June before hitting the U.S. in July.

Zayn Malik's face screams "REGRET" in the first pics of him since he quit One Direction -- at least that's how millions of fans see it.

But we have a feeling Zayn will be just fine -- as long as he's cool with the state fair circuit.

Count Justin Bieber as one of the legions of One Direction fans who are broken up because Zayn Malik quit the band.

Biebs was leaving Bar 20 at the Grafton Hotel in WeHo Thursday when our photog gingerly asked how he felt about One Direction-less. Bieber echoed the hurt that millions of tweens are enduring.

Biebs also dropped some big news, although it did seem pretty obvious ... he'll be walking Floyd Mayweather to the ring for the big fight with Manny Pacquiao.

Zayn Malik's face ... hours after he quit One Direction ... said exactly what millions of 1Ders were thinking -- "OMG, what the hell have I done?"

Zayn was out in North London on Wednesday afternoon ... settling into retirement, at 22 years old.

While he reportedly cited "stress" as the reason he originally dropped out of the band's tour -- word is he was worried his lifestyle on the road was messing up his life with his fiancée.

The band plans to continue without him and finish its tour before the next album comes out.

Meanwhile, Zayn will be wondering if he's the next Timberlake ... or the next Kirkpatrick.

Zayn Malik has found a new direction and it's all about stepping out of the spotlight ... he says he's leaving One Direction to be just a regular guy for awhile.

The band announced Malik's exit via Facebook Wednesday but Zayn says even though the last 5 years have been a dream, he needs to go with his gut and chill ... you know, just like every other normal 22-year-old pop icon.

The rest of the group says it's a huge bummer, but they respect his decision and plans to go on as a foursome with Niall, Harry, Liam, and Louis picking up the slack.

Producer Simon Cowell also sang Zayn's praises but he's definitely holding his chin up and assuring the die-hard fans they have nothing to fear -- the band will go on.

As for Zayn's reason to splitsville ... last Thursday he bowed out of the band's world tour due to "stress," but rumors swirled his lifestyle threatened his relationship with his fiance.

The band vows to continue to tour as a lead up to their fifth album.

Kobe did it ... LeBron did it ...and now Harry Styles is also teaming up with the tribe for some good old fashioned athletic competition -- at a Jewish Community Center.

TMZ Sports has learned ... the One Direction star hit up the Westside JCC in L.A. Thursday to play a little indoor hockey with some friends.

We're told Styles was one helluva player -- scoring several goals during the hour-and-a-half long session.

Fun Fact -- there were actually 6 Jews in the NHL last season! Who knew?