Wire Image / WENN 1 / 5
Wire Image / WENN 1 / 5

By Kat Giantis

Another day, another swirling rumor about Scarlett Johansson's post-Ryan Reynolds love life, although we'll leave it to you decide whether this one is an upgrade or a downgrade from those recent reports linking her to funnymen Jason Sudeikis and Justin Long.

"Scarlett Dating Sean Penn," pronounces the cover of the latest Us Weekly, which claims the "undercover lovers" began seeing each other a few weeks after her December split from Reynolds.

Things supposedly heated up last weekend, when the actress was seen enjoying a tête-à-tête with the altruistic but pugilistic and romantically bitter Oscar winner during a celebrity-stuffed "Black Swan" bash at the Sunset Tower Hotel in Los Angeles.

According to the mag, ScarJo, 26, and Sean, 50, sucked on cigarettes outside the shindig as they "conspired" to leave together in a way that wouldn't arouse suspicion about their "status as a couple."

Their ingenious plot: to go back inside the party, ignore each other, then stagger their exits by five minutes, a plan that was reportedly hatched while Penn "caressed" Johansson's arm and jacket.

Their ostensible "secret sexy fling" came a month after their first hookup, says the mag, with a spy alleging that they also rendezvoused on Jan. 4 in a bungalow of the Chateau Marmont in Los Angeles.

"She's smitten with him," enthuses a source.

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Not so, says Johansson's rep, who has repeatedly insisted the star is not dating anyone at the moment.

"There is no truth to this rumor," her spokesman assures Wonderwall. "They are friends and have been friends for years."

Word is, the two were merely discussing earthquake-devastated Haiti while getting a nicotine fix.

Penn, of course, has spent much of the last year doing relief work in Haiti, although he did find time to take some court-ordered anger management classes and finalize his divorce from Robin Wright after 20 years together.

In the fall of 2009, he stepped out with Sports Illustrated swimsuit model Jessica White, a hookup that came a few months after he was linked to "Swan" star Natalie Portman for a hot minute, a rumor that she adamantly denied.

Scarlett, for her part, was seen in the company of estranged hubby Reynolds on Jan. 28, having what Us described as a "rollercoaster conversation" on the patio of the Chateau Marmont.

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