The Celtics and representatives for captain Paul Pierce opened talks on a new contract Thursday and progress is being made, sources told ESPN.com's Marc Stein.

Pierce received inquiries from "a few" other teams, but Boston is the only team he's currently speaking with, the sources said.

He joined this summer's free agent class by deciding to opt out of the final year of his contract, which would have paid him $21.5 million next season.

Boston can give Pierce a four-year deal worth $96 million.