Both physical and mental skills are needed to play tennis. The physical skills include athleticism, speed, balance and hand-eye coordination. The mental skills include decision making, motivation, concentration and competitiveness.
Tennis is a physical sport, so athletic ability and a good level of fitness are required. Speed is also important, particularly explosive speed in order to get from one part of the court to another quickly. Balance is required to get to the ball and make a shot, as is hand-eye coordination; the player needs to be able to accurately anticipate the direction of travel of the ball as early as possible.
Like other sports, motivation and a competitive spirit are both good qualities to have in a tennis player. It is a very technical and tactical game, so effort is required to remain focused, and such effort requires motivation and concentration. And to win against other experienced players, a good awareness of the tactics of the game are required, along with good decision making skills so that the right tactics, or shots, are employed at the right time. In some respects this is a problem-solving ability, for example, working out how to return the first service of an opponent, or deal with a top spinning forehand.