Bookmakers set odds for Grand Slam events by analyzing a combination of factors, including player statistics, head-to-head records, recent performance, surface preference, injury updates, and overall form. They utilize complex algorithms and statistical models to predict potential outcomes and assess the probability of each player's success. Additionally, bookmakers consider market sentiment and adjust odds based on the betting patterns and volume of wagers placed, ensuring their exposure is managed while aiming to attract balanced betting on both sides of the market. This dynamic process helps them establish competitive odds that reflect the true probabilities of players winning.