In 'Love and Other Drugs,' Jake Gyllenhaal and Anne Hathaway play opposites who attract and then undress one another with pretty steamy frequency. It's a stark departure from their previous onscreen coupling, in 'Brokeback Mountain,' in which the pair first gets busy in the backseat of a car, before dwindling into a loveless marriage.

How does Jake and Anne's romantic reunion stack up compared to other leading men and ladies who've taken a second shot (or shot a second take) at love, Hollywood-style? We're not talking about when characters stay together for the sake of the sequel, but when two movie icons double down on their onscreen chemistry in completely new roles. Here's nine more of them, with our take on which films sizzle or fizzle.

1. Richard Gere and Julia Roberts

The movies: 'Pretty Woman' (1990) and 'Runaway Bride' (1999)

Plot points: The first one's about a commitment-phobic hooker who refuses to kiss her clients on the mouth. The second's about a commitment-phobic small-town girl who refuses to meet her fiances at the altar. Oh, and Richard Gere lives in a place with a sweet balcony both times, go figure.

Chemistry assessment: You really can't meet cuter than picking up a streetwalker in downtown Los Angeles, and you really can't be cuter than these two are in 'Pretty Woman' when he teaches her how to enjoy champagne and strawberries, or surprises her with a diamond necklace. As for 'Runaway Bride,' props for the twist ending (she proposes to him!), but for some reason this movie just reminds you that the age difference in play here is kinda icky.

The winner: 'Pretty Woman' runs away with it.
2. Leonardo DiCaprio and Kate Winslet

The movies: 'Titanic' (1997) and 'Revolutionary Road' (2008)

Plot points: 'Titanic,' as you may have heard, is about how an iceberg can sink a ship -- but never their love for one another! In the lesser-seen 'Revolutionary Road,' Kate and Leo play Eisenhower-era idealists who dream of moving to Paris but ultimately feel trapped by their suburban existence. Ironically, in both flicks, all they want to do is get across the damn Atlantic.

Chemistry assessment: So hot in 'Titanic' that they could've just melted the stupid iceberg, and they don't lose much of that heat in 'Revolutionary Road.' Their sex-on-a-kitchen-counter scene in the latter may even out-steam their sex-in-a-car scene in the former.

The winner: 'Revolutionary Road' puts up a good fight, but come on -- it's 'Titanic.'

3. Mel Gibson and Rene Russo

The movies: 'Lethal Weapon 3' (1992) and 'Ransom' (1996)

Plot points: In 'Lethal Weapon 3,' the two must track down a dirty cop because, well, they're cops. In 'Ransom,' the two must track down a dirty cop because, well, "GIVE ME BACK MY SON!"

Chemistry assessment: 'Lethal Weapon 3' is a case study in flirtation through trash-talking, punctuated by a stellar scene in which the two compare bullet wounds (and then, of course, immediately start making out). They play a well-matched married couple in 'Ransom,' but are too distracted by their missing child to make out much.

The winner: 'Lethal Weapon 3,' because you don't watch a movie like 'Ransom' for the witty banter or the big sex scene.

4. Kate Hudson and Matthew McConaughey

The movies: 'How to Lose a Guy in 10 Days' (2003) and 'Fool's Gold' (2008)

Plot points: She's a magazine reporter and he's her unwitting feature-story foil in the former flick. We're still not sure what 'Fool's Gold' was supposed to be about.

Chemistry assessment: Both times around, Hudson and McConaughey do the whole we-hate-each-other-but-really-we-like-each-other thing. The main difference is that in 'Fool's Gold,' they mostly do so in bathing suits.

The winner: 'How to Lose a Guy in 10 Days' -- a cover story Hudson's character should've read in 'Fool's Gold.'

5. Drew Barrymore and Adam Sandler

The movies: 'The Wedding Singer' (1998) and '50 First Dates' (2004)

Plot points: Pretty straightforward, 'The Wedding Singer' is about a wedding singer who wants the wedding waitress he can't have. In contrast, '50 First Dates' sports an uber-high-concept plot involving memory loss and, well, 50 first dates. Sandler's slightly stalkerish in both.

Chemistry assessment: When you're as awkward as Adam Sandler, pitching woo via a silly song, as he so memorably does at the end of 'The Wedding Singer,' is a good way to go. It also helps to try to win a woman over in the romantic environs of Hawaii, as he does in '50 First Dates.'

The winner
: Stalkerishness aside, these two really do make the cutest cinematic couple. Give it to 'The Wedding Singer' and bring on the threequel!

6. Ethan Hawke and Julie Delpy

The movies: 'Before Sunrise' (1995) and 'Before Sunset' (2004)

Plot points: Yes, we're breaking our own rule here. But the whole point of 'Before Sunset' -- in which Hawke and Delpy play thirtysomething versions of their original college-age characters, who spent one fateful night ('Before Sunrise,' get it?) wandering the streets of Vienna together -- is to examine how two people's chemistry can change over the years, so we'll make an exception.

Chemistry assessment: Both times around, the dance of attraction is delicate, imbued with the fear of rejection and heartachingly authentic.

The winner: This is a toughie, but we're going with 'Before Sunset' because of its sexual-tension cliffhanger. We're still dying to know if they did it or they didn't.

7. Keanu Reeves and Sandra Bullock

The movies: 'Speed' (1994) and 'The Lake House' (2006)

Plot points: 1. "There's a bomb on this bus!" 2. "I write to dead people." (Or something like that.)

Chemistry assessment: 'Speed' is chockablock with moments of in-your-face, high-octane sex appeal, like when Reeves rescues Bullock from the bus. Or when he rescues her from the subway. Or when he rescues her from making 'Speed 2.' (Ha, ha.) 'The Lake House,' by contrast, is low-impact lovey-dovey; as star-crossed lovers living two years apart, they don't even share screen time until the end, although it is a doozy when they finally do meet.

The winner: 'Speed,' one of the few action films whose romantic subplot felt genuine and earned. Plus, Reeves and Bullock are just hot together; whose idea was it to make them not share screen time the second time around?

8. Meg Ryan and Tom Hanks

The movies: 'Joe Versus the Volcano' (1990) and 'Sleepless in Seattle' (1993)

Plot points: In 'Joe Vs. the Volcano,' Ryan plays three female characters -- Joe's coworker and two of his boss's daughters -- all of whom enjoy an attraction with Hanks' Joe. Unfortunately, Joe's scheduled to jump into a volcano. In 'Sleepless,' Ryan develops an attraction to Hanks' widow after hearing him on a radio call-in show. Unfortunately, he lives on the other side of the country.

Chemistry assessment: Hanks and Ryan have made an art out of bad romantic timing (including in their third flick, 'You've Got Mail,' in which they play bookselling rivals by day who are unwittingly best online buddies at night). While the existentialist antics of 'Joe' made for some cute interactions, the final scene of 'Sleepless' atop the Empire State Building is a romance classic.

The winner: 'Sleepless,' duh. Hanks and Ryan wrote the book on chemistry in absentia.

9. Katharine Hepburn and Spencer Tracy

The movies: 'Woman of the Year' (1942) and 'Without Love' (1945)

Plot points: Hepburn and Tracy co-starred in nine films throughout their respective careers; these are the first two in which they played romantic leads opposite one another. Both movies ponder the whole love-and-marriage thing. In 'Woman of the Year,' the two rush into marriage, then realize the whole ever-after thing may take a little work. In 'Without Love,' they play a widow and a scientist who marry for practical reasons, then get around to falling in love later.

Chemistry assessment: Bickering never looked so good as when Hepburn and Tracy did it, and they did a lot of it in 'Woman of the Year.' Hepburn even makes crazy look good in that movie, as when she breaks into her estranged husband's new home to make him breakfast.

The winner: 'Woman of the Year' was romantic comedy at its best.