 Complete the following phrase:  Before the start of the season, Hamilton announced he would not be exercising his option of switching his car number to 1, as was his prerogative as reigning World Champion, and would instead continue to race with his career No. 44. It was the first season since , when Alain Prost retired from the sport following his fourth and final World Drivers Championship title in , that the field did not contain a car bearing the No. 1. Hamilton dominated the season, winning ten races finishing on the podium a record seventeen times as he matched his hero Ayrton Sennas three World Championships titles. The rivalry between him and Rosberg intensified, climaxing in a heated battle at the 