Lil Wayne has a date in a Manhattan courtroom, but DNA science will take center stage.

A hearing on a DNA profiling technique used in the rapper's 2007 gun-possession case was due to start Wednesday(October 21).

It concerns a process used for identifying people from tiny amounts of DNA — including some that prosecutors say ties the rapper to a gun found on his tour bus after a concert.

The 27-year-old has pleaded not guilty. He faces at least 3 1/2 years in prison if convicted.

The hearing aims to establish whether what's known as low copy number DNA profiling has general scientific acceptance.