Lovato replaces tour opener Adam Lambert with Nick Jonas

Demi Lovato replaced Adam Lambert with Nick Jonas on her tour

Washington D.C.: Looks like Adam Lambert will no longer be opening for Demi Lovato on her world tour as she replaced him with Nick Jonas.

The 23-year-old's manager, who also manages Jonas, has convinced her to drop the 'Ghost Town' hit-maker, TMZ.com reports.

A source close to the 33-year-old American singer said that Lovato's move was "very unprofessional and unethical."

Earlier the 'Let It Go' hit-maker had worked out the financial details of the arrangement with Lambert before replacing him.

Demi was likely to announce her tour last week, but she has delayed it due to the change made in the opening act.