The serve must land in the diagonal service box
Padel rules · Serving
Like tennis, the serve is cross-court. The ball must bounce inside the diagonally opposite service box. If after bouncing in the box the ball hits the wire mesh fence before the returner plays it, it is a fault. If it touches only the side glass after a valid bounce, it is in play.
📘 Category: Serving. This is one of the rules that most often confuses players coming from tennis or pickleball.