Rafael Nadal and Novak Djokovic, the world’s top two, are this week vying for the year-end number one ranking as London hosts the ATP World Tour Finals for the fifth time.
Andy Murray, Britain’s first Wimbledon men’s singles champion for 77 years, misses the tournament at the O2 arena as he recovers from back surgery.
The tournament sees the world’s top eight players split into two groups, with the top two from each progressing to the semi-finals.
After winning the French and US Open titles since returning from injury in February, Nadal will clinch the year-end number one ranking if he wins two matches in London.
Tournament organisers say ticket sales for the two daily sessions at the 17,800-capacity arena have matched those of previous years,
