When betting on a player's quarter-final match in a non-Grand Slam event, several key factors should be considered. First, assess the players' current form, including their recent match results, physical condition, and any injuries that may impact performance. Analyze their head-to-head records, as past encounters can provide insights into how they match up against each other. Consider the playing surface, as some players excel on specific surfaces (e.g., clay, hard, or grass). Look into the players' mental toughness and experience in high-pressure matches, particularly in knockout stages. Additionally, factor in external conditions such as weather and crowd support, which can influence performance. Lastly, review betting odds and market sentiment to identify potential value bets.