[qwery]

You could do a clean-room implementation[0] of Michael Jackson's Thriller and the rights holders could still take you to court and have a good shot at winning. You could have never heard Thriller, come up with an obvious[1] melodic phrasing that some lawyers reckon sounds close enough and still get sued.

Of course, none of that makes it copyright infringement, only the (would-be) judge does.

[0] The product of which is roughly equivalent to a cover

[1] obvious to a musician or composer