Definition
An upline cut is a handler's vertical attack up the sideline (or up the central lane) — a cut into the Power Position Channel rather than back into dump space. It is most often the answer to a defender who is overprotecting the under or the reset, leaving the upfield space behind them.
In Context
The upline is the punishment cut for a defender who has cheated to the wrong side of the Dump Handler. If the defender is shading toward the dump space, the handler attacks vertically — past their shoulder, into the lane in front of the disc — and receives in stride.
The window is small. The thrower's release has to be early — the upline opens for two or three seconds and closes hard. "The window is in their first three steps — not the last three." See 4 Lines - Upline Cut for the dedicated drill.
The upline is one of the cleanest ways to enter the Power Position Channel from a handler position. It is also one of the most common entry points into a Give-and-Go sequence — receive upline, give it on, follow your throw.