Last night I got clocked by a sub in my singles league. I have previously learned not to overestimate players based upon them having a good warm-up, but it seems last night I underestimated one. The first couple of games were played even, and then his level picked up considerably. I tried to quickly raise my game, but it just wasn't happening for me and I actually began to play much worse. Question: What can I do during a warm up to get a true idea of the skills and strokes of the opponent (without being obnoxious)?