Last Updated: 11/11/18 5:58pm
Marin Cilic has largely produced his best tennis on the Grand Slam scene in 2018.
The experienced Croatian began the year with a run to the Australian Open final - his third major showpiece - where he was eventually beaten in five sets by Roger Federer.
Quarter-final runs at the French Open and Wimbledon came either side of a shock second round defeat at Wimbledon, having arrived at the All England Club full of confidence after winning at the Queen's Club.
But that victory is his only title coming into the ATP Finals, where he has only managed one victory in his three previous appearances.
An impressive display against Novak Djokovic at the Paris Masters suggested he could be ready to improve his record at London's O2.