3. Karen Khachanov
It might be hard to back Karen Khachanov to win anything at the moment, considering the fact that he has been out of form for more than a year. However, the Russian is a better player than his last string of results show, and the conditions in Rotterdam are extremely suitable to his style of play.
The best results of Khachanov's career have come on indoor hard, so I wouldn't be very surprised if he has a deep run this week - or even wins the title.
The 23-year-old has a lot of beatable players in his quarter. Gael Monfils and Fabio Fognini are the most dangerous opponents that he could face before the semifinals, and on a good day, the Russian can defeat both of them.
His serving power should prove to be a very important asset on these courts. If he is able to stay away from unforced errors on his return games, then I expect him to have a good tournament this week.