Jennifer Aniston's new movie "The Break Up" is number one at the US box office - despite being panned by critics.

The romantic comedy - which stars the former "Friends" actress and her real life boyfriend Vince Vaughn - made $38.1 million in its first three days of release.

The movie also gives Aniston her first real taste of box office success. Recent releases, "Derailed" and "Rumor Has It" only made $36 million and $43 million respectively.

However, "The Break Up" has been savaged by film critics. In its review, the Wall Street Journal asked: "What's a smart comedienne doing in such a dumb movie?"

Another critic sniped: "A romantic comedy that is both short on romance and comedy."

The movie was also panned by test audiences. A source told America's New York Post newspaper: "The original screenplay had Jennifer and Vince's characters breaking up at the end. So it was shot that way - but test audiences hated it. It tested really, and I mean really, badly."

As a result of the negativity, the lead actors had to re-shoot parts of the film, reportedly costing the studio millions.

The source added: "The new ending has them getting back together in the end. It should really be called "The Make Up." People want to see Jennifer happy after the tough time she has had with Brad Pitt and Angelina Jolie."