Another musician is being sued over copyright infringement.

FOX's Michelle Pollino reports: 

A Pitbull song is the latest target of a music copyright lawsuit, centering on the song "Timber" featuring Kesha.

William Underwood is part owner of the old school funk song "Weak at the Knees." Underwood insists Pitbull sampled 'Weak' for his hit "Timber." The core of the lawsuit is the guitar riff. Take a listen and judge for yourself. This is 'Weak at the Knees'... 

This is "Timber"...

Pitbull's not being sued, just his publishing company.

Michelle Pollino, FOX News.

Follow Michelle Pollino on Twitter: @MichelleFOXEnt