Back on? Scarlett Johansson poses backstage with ex-boyfriend Sean Penn at Guys Choice Awards

They supposedly split up just a few weeks ago.
But last night  was back on the arm of Sean Penn as they posed back stage at the Spike TV 2011 Guys Choice Awards in Los Angeles.
Sean, 50, was snapped with his arm around 26-year-old Scarlett with a glass of water in hand, raising the question of a reunion between the pair.

Setting tongues wagging:  posed backstage with Sean Penn at Spike TV's Guy Choice Awards on Saturday night, just a week after news they had split

Earlier they avoided posing together on the red carpet, with Sean sneaking in the back door, while Scarlett arrived in a stunning white Valentino dress.
At the event Penn accepted the Guy Movie Hall of Fame award from Robert De Niro for his role in Fast Times on Ridgemont High.
Sean and Scarlett set off a media frenzy after they went on a romantic getaway to Cabo San Lucas earlier this year.
They were also spotted together on a flirty lunch in a Los Angeles restaurant in March of this year when Scarlett rested her legs on the actor's lap.

Going solo: Earlier Scarlett walked the red carpet alone while Penn snuck in the back door before collecting an award at the event

Speculation that there has been trouble brewing in their fledgling relationship began when Scarlett was noticeably absent from the premiere of Penn’s latest film, The Tree of Life, at the Cannes Film Festival last month.

A source then confirmed to People Magazine last week that the pair has indeed called it quits and are no longer an item.

Hollywood is abuzz with speculation about why the pair split after just two months, but the gorgeous actress stuck to industry chatter on the red carpet last night.

Fighting form: Johansson was keen to talk about her training on the Avengers  at the Spike Awards in L.A, but not about Penn

Old boys: Robert De Niro presents Sean Penn with his award

The event was held at Sony Studios in Culver City and Justin Timberlake, Mila Kunis, Jennifer Aniston and Cameron Diaz were among the A-List guests in atendance.
Scarlett was keen to impart an insight from the set of The Avengers, a canny move considering the moribund status of her movie career versus her fervid love life of late.

She told Just Jared: 'I just flew in from New Mexico, where I’ve been shooting The Avengers. A bunch of the cast is here tonight but I’m here to support the troops. Chris Evans and I are presenting.'
'We’re right in the middle of scenes and figuring a lot of stuff out. I’ve been training a lot and doing all sorts of exercises.'
Her new fitness regime is just another thing she now has in common with one of the beauties at the event, another newly minted singleton Cameron Diaz, 38.
The blonde is reported to have split from her baseball pro lover Alex 'A-Rod' Rodriguez, 35 , but betrayed no sign of sadness at the high-spirited event, despite opting for a funeral black suit.

Ladies man: Timberlake had fun presenting the Holy Grail of Hotness Award to co-star Kunis

Holy Grail: Kunis with her flattering award

The honour went to Black Swan temptress Mila Kunis, 28 , who accepted the award from her Friends with Benefits co-star Justin Timberlake, 30.
Jennifer Aniston, 42 , meanwhile, was honoured with the Decade of Hotness Award and earned a whoop from friend Jim Carrey, who scooped the Funniest MF gong, which was presented by Diaz.
Timberlake, again a member of the newly single brigade after splitting from Jessica Biel, had taken care not to let his female counterparts upstage him in the style stakes.
Justin looked sharp in a John Varvatos leather jacket, Dolce and Gabbana shirt, Nice collective khakis, All Saints boots set off with a Cartier watch.
The cheeky star also had fun with the show's choice of award, a pair of stag's antlers.

Mirth: Jim Carrey accepts the Funniest MF Award with violinist Neil Hammond

Fighting fit at forty: Mark Wahlberg accepts his award

Brass Balls: Rolling Stone Keith Richards was tickled pink by his award

Timberlake has been linked to a string of beauties including Olivia Wilde and most recently Ashley Olsen, since splitting with Biel.
So it's clear he's not afraid of mining his reputation as a ladies man for a laugh.
And Mark Wahlberg, who turns 40 tomorrow, started his celebrations by picking up the award for Best Guy Movie of the Year for The Fighter.
Rolling Stone Keith Richards bagged the most humorous trophy of the evening - the Brass Balls Award, and the 67-year-old rocker appeared to appreciate more than his many gold discs.