The Czech tennis stars Karolína Plíšková and Petra Kvitová have “swopped” coaches. Plíšková, the world number six, has just announced that she is to begin working with David Kotyza, who until January trained Kvitová. The latter, meanwhile, has hired Jiří Vaněk, who Plíšková parted company with in mid-November. World number 11 Kvitová is a two-time Wimbledon winner. Plíšková reached the final of the US Open this year.