The free energy profile for the association of 18C6...K+ in water is investigated employing the umbrella sampling technique. By a specific bias potential the encounter geometry of crown and ion is restricted to a mutual approach along the crown’s symmetry axis. The most striking feature in the computed W(r) is a solvent-bridged pair 18C6...H2O...K+ as a distinct local free energy minimum. The bridging water molecule-strongly hydrogen bonded to 18C6 and already preformed without an ion present-is capable of simultaneously and efficiently docking with the K+ ion. The presence of a free energy activation barrier is in qualitative accord with experimental findings. Discrepancies with former theoretical results lacking such a barrier are discussed.