Justin Baldoni‘s lawyer has a challenge for Blake Lively … he says her testimony should be live-streamed in the world’s most famous arena — Madison Square Garden!!!

Baldoni’s attorney, Bryan Freedman, tells TMZ … “If Blake Lively is really serious about testifying for the world to see, let’s live stream it in Madison Square Garden and give the money to the domestic violence survivors.”

Freedman’s challenge comes in response to Blake’s lawyers revealing she absolutely plans to take the stand if their lawsuit actually makes it to trial … and his idea isn’t going over so well in Blake’s camp.

Meanwhile, Blake’s lawyers Esra Hudson and Mike Gottlieb tell TMZ … “This is a case about what happened to Blake Lively when she raised claims of sexual harassment on set and the retaliation that followed. Of course she will testify.”