They had just eaten Northampton alive at Franklin Gardens for the benefit of a bonus-point and were expected to feed on the English club again at Ravenhill in round four.
Instead, Mark Anscombe's men were given a wake-up call that was largely of their own making. They simply thought the job was done over there.
The Saints came with a solid game-plan. Ulster facilitated them by making a host of simple errors.
Glasgow are without a single win. They should provide the perfect fodder for Ulster's need for a winning return.
Ulster: J Payne; A Trimble, D Cave, P Wallace, C Gilroy; P Jackson, R Pienaar; T Court, R Best, J Afoa, L Stevenson, I Henderson, R Diack, C Henry (capt), N Williams.
Glasgow: P Murchie; S Maitland, A Dunbar, P Horne, DTH Van Der Merwe; D Weir, H Pyrgos; R Grant, D Hall, M Low, T Ryder, A Kellock (capt), J Eddie, R Harley, J Strauss.
Ulster v Glasgow
TONIGHT, SKY SPORTS 2, KO 8.0