This document presents the Glicko 2 1 pairwise comparison method for estimating skills of tennis players, both on serve and return. It starts with review of existing literature on modelling tennis skills. Next, it gives an overview on Glicko2 Tennis model, followed by an example of Scala code for calculating skills of tennis players. Later on, it demonstrates three examples of practical applications for tennis skills. The first one, is a study on historical skills of Roger Federer and Novak Djokovic. The second case, is about calculating probability of winning a point on serve and return at the beginning of a tennis match. The last example, illustrates how to predict outcomes of tennis matches using skills of tennis players on serve and return. Finally, Glicko2 is discussed in a context of potential improvements in modelling skills in tennis.