I've come to the conclusion to not pay too much attention to groundstrokes during warm-ups. Too often guys that could barely sustain a medium paced rally during warm-ups somehow find their range and never miss once the game starts. One thing I have noticed though during warm ups, guys that feed good overheads and hit overheads with medium pace right back to me when I'm feeding are the ones to watch out for. If my opponent is slamming overheads over the fence during warm ups, I start to lick my chops. These guys are typically slashers and can't get more than 3 balls back in play. This is my experience (3.5 and 4.0 doubles) just curious if others have noticed this.