The 1973 Commercial Union Assurance Masters was a tennis tournament played on indoor carpet courts at Hynes Auditorium in Boston, Massachusetts in the United States. Mateflex is a soft plastic, interlocking tile court, with the slower ball speed of clay but the low maintenance of a hard surface. It was the fourth edition of the Masters Grand Prix and was held from December 4 through December 8, 1973. Ilie Năstase won his third consecutive Masters title and earned $15,000 prize money.
Finals
Singles
Ilie Năstase defeated Tom Okker 6–3, 7–5, 4–6, 6–3
It was Năstase's 24th title of the year and the 58th of his career.