The buddy-cop movie has been around for decades, typically starring two mismatched male characters, except for those few instances where the buddies are actually a man and a dog, as in 1989's "K-9" and "Turner & Hooch."
Now Sandra Bullock and Melissa McCarthy are getting into the mix with "The Heat," and advance ticket sales show fans are warming quickly to the concept.
Movie website Fandango says "The Heat," from 20th Century Fox, is the most popular offering this weekend, comprising 35 percent of nationwide ticket sales.
"It's taking a genre that very much appeals to one demographic, and inserting stars who appeal to another demographic," which makes the film equally appealing to men and women, said Dave Karger, chief correspondent for Fandango. "It has the action and it has the comedy which the guys are probably going to go for, then the female-friendship angle, too. Women just love Sandra Bullock and Melissa McCarthy and are excited to see a big summer movie with two women in the lead."
The standard buddy-cop formula is at play here, with Bullock playing an uptight, lonely FBI agent who's paired with McCarthy's foul-mouthed, no-nonsense Boston police officer to take down a drug dealer. But having women play the incompatible cops makes the film unusual, if not downright groundbreaking. (The 1988 movie "Feds" focused on the comedy of two women accepted to the FBI training academy.)
"As insane as it sounds, it's such a unique thing to have two women," Karger said. "They thought of putting a dog in there before they thought of putting a woman in there, but that's Hollywood for you."
It's not only unusual to see two women take on the buddy-cop genre, but two women over 40 opening a big summer picture, said Tatiana Siegel, who covers the film industry for the trade publication The Hollywood Reporter.
"You might see two women in a movie like a Sundance movie, but this is a major, heavily marketed summer movie with franchise potential that in the past would have featured two men starring in it," Siegel said.
But she adds that the film is no great risk for Fox because of its relatively modest budget and the star-power of McCarthy and Bullock.
Karger said "Bridesmaids" cleared the way for this film: "Clearly the massive success of 'Bridesmaids' allowed a movie like this to exist."
"The Heat" is directed by "Bridesmaids" director Paul Feig, who declined to be interviewed for this story.
Box-office analyst Paul Dergarabedian predicts that "The Heat" could beat its buddy-action competitor, "White House Down," also opening Friday, which stars Channing Tatum and Jamie Foxx.
If "The Heat" wins the box-office race, it would be "a huge coup" for actresses, Siegel said.
"Actresses in general are paid less than their male counterparts," she said. "If this movie finishes first, it speaks volumes about the work of two actresses and how audiences are more than willing to support movies like this."
AP Entertainment Writer Sandy Cohen is on Twitter: www.twitter.com/APSandy .