Serena Williams Photos: Picture Gallery of Strokes

From her big knee bend, Sernea gets a powerful leg thrust that has lifted her off the ground here. Through the kinetic chain, the energy from that leg thrust has also straightened Serena's elbow, which will momentarily result in the final link in the chain, the extremely fast whipping forward and upward of the racquet, via the wrist, that is the natural culmination of all of the energy delivered from the larger parts of her body.

Serena is doing a good job of continuing to look up at the ball. Her left arm is tucking itself out of the way. She is using a Continental grip, the grip most commonly used for advanced first serves.