The final tournament of the 2018 season kicks off Sunday: it's the Nitto ATP Finals, the year-end championship with just an eight-man field.
The top eight players in the ATP's Race to London qualify for the tournament, but two of those players—Rafael Nadal and Juan Martin del Potro—had to pull out with injuries. Their absence means No. 9 Kei Nishikori and No. 10 John Isner get into the field.
There's also a doubles event, which features the top eight doubles teams in the world.
The eight-man singles field is split into two four-man groups. Their tournament seeds are in parentheses.