Yanga-Mbiwa has helped Roma record two clean sheets so far against both Cagliari and Verona as well as playing well in a 2-1 victory at Parma.
He made 28 starts in the Premier League for Newcastle but was used out of position most of the time.
Roma's Francesco Totti became the oldest goalscorer in Champions League history as Manchester City escaped with a draw from their Group E clash.
Totti, 38, defied his age with a sublime finish to cancel out Sergio Aguero's early penalty for City at the Etihad Stadium.
It was little more than the in-form Serie A side deserved for a high-quality display of attacking football, and Yanga-Mbiwa was as good as anyone on the field.
This asks the question - why didn't Alan Pardew get the best out of a player who has won French homours and is well thought of across Europe?
The Serie A club have the option to buy Yanga-Mbiwa at the end of the season but are keen to get the deal pushed on early.
The Magpies paid around £6.7million to Montpellier for his services in January 2013.
But Alan Pardew didn’t rate the player and used him out of position as a right-back.
However. Roma boss Rudi Garcia is delighted with the 25-year-old.