There's a serious environmental crisis gripping Hollywood, one that won't be solved by your favorite star trading in an Escalade for a Prius. We're talking, of course, about the rapidly shrinking celebrity dating pool, the effects of which apparently caused a bit of a kerfuffle between two big-name actresses last weekend in New York.

According to OK!, Drew Barrymore and Kirsten Dunst had an uncomfortably close encounter when they both turned up backstage to catch James Franco's hosting gig on "Saturday Night Live."

The cause of their alleged unease is the inexplicably irresistible piece of man candy that is Justin Long, who split from Barrymore in July after nearly a year of constant tongue contact and has lately been spotted sharing his saliva (hey, he's a giver) with Dunst.

"Drew and Kirsten had a really awkward run-in," a spy claims to the mag, which says that Barrymore was on hand to support BFF Cameron Diaz, who was reprising her cougar-riffic cameo from last spring, while Dunst was there for her "Spider-Man" co-star Franco.

"James had to deflect the situation by making a joke and walking away with Kirsten," adds the eyewitness, "while Drew then fumed about it to Cameron."

Drew guides Chace through the crowd at a New York concert on Sept. 20.

OK! says the actresses also crossed paths at the post-show party at a New York club, where musical guests Kings of Leon performed for a crowd that included ubiquitous "Gossip Girl" pretty people Chace Crawford, Ed Westwick, Penn Badgley and Blake Lively.

"Both Drew and Kirsten were there," relays a club patron. "But Kirsten didn't want to be near her, so they stayed far away from each other the entire night."

The supposed game of keep-away proved difficult because of their mutual need for nicotine, with both stars frequently heading outside to puff on their cancer sticks, says the magazine.

People, however, believes Barrymore's focus at the bash wasn't on the possible new squeeze of her ex. Instead, she was busy getting her flirt on "all night" with a mystery man.

In between making eyes at the unknown guy, Drew also apparently hung out with Crawford, downed beers with Ellen Page (she's directing the "Juno" spitfire in the roller derby flick "Whip It!") and buddied up to Westwick.

In a very Chuck Bass kind of moment, the British actor offered Barrymore his lighter and later escorted her through the crowd once she'd satisfied her smoky craving.

Dunst, for her part, laughed off talk of a Long hookup in the October issue of Harper's Bazaar, calling the rumors "the funniest thing on the planet Earth. I don't know him from Adam. I met him once, and he and his friends were kind enough to walk me home. I've never seen him since."

That might have been true at the time, but in recent weeks she's been photographed laughing with the actor-cum-Mac guy over lunch in Los Angeles and was reportedly spied polishing his tonsils at a Los Angeles music festival.