Photo Study of James Blake's Strokes

James shows outstanding extension here as he meets his serve. The strong knee bend with which he begins his serve leads to the powerful upward leg thrust that has lifted him off the ground. Every inch higher that you meet a ball on serve gives you a significantly greater margin of clearance over the net. This photo also captures especially well how James is striking upward and across the ball to produce the standard mixture of topspin and slice for a power first serve.

Can you spot the one arguable flaw in James's technique here? His head has pulled down, so that he's looking away from the ball. Many servers get outstanding results despite not looking up throughout the swing, but for many players, prematurely pulling the head down results in pulling the racquet down, which can in turn cause off-center contact and pull the ball down just enough to put it into the net.