Mr. Meek Plays Polo  (Paperback, Clifford D. Simak)

The story revolves around Homer Meek, a mild-mannered and unassuming man who unexpectedly finds himself thrust into a peculiar situation. One day, Homer Meek receives a mysterious invitation to play polo. However, this isn't the traditional sport of polo that one might expect. Instead, it's a game played on the backs of large dinosaurs. Initially bewildered by the invitation, Meek eventually decides to accept the offer. He is transported to a strange alternate world where dinosaurs still roam the Earth, coexisting with humans. Meek learns that he has been chosen as a replacement player for the polo team, which is in dire need of a skilled participant. Despite his lack of experience and expertise in polo, Meek decides to give it his best shot. He is assigned to ride a triceratops named Arabella, who proves to be quite temperamental. Meek struggles to control Arabella and adapt to the fast-paced and chaotic nature of the game.