Darren Moore has said sorry to Albion's travelling fans after Leeds steamrolled the Baggies 4-0 at Elland Road.
Albion were behind after a matter of seconds when Pablo Hernandez's long-range strike beat Sam Johnstone.
Patrick Bamford added a second before the break before he put the game out of Albion's reach after half time with a third.
It then got worst for Albion in injury time when Ezgjan Alioski slotted home a fourth in injury time.
"It’s obviously really disappointing," said Moore.
“We gave ourselves a mountain to climb in the game.
“It was an uphill battle after the two first-half goals.
“You don’t ever want to go a goal down early in the game, especially coming up here.
“It’s a result that’s a hurtful result but we have to take it on the chin.
“We’ll have to pick the bones out of it.
“We can only apologise to the fans who travelled for that performance.
“I don’t think any of us saw that coming. We didn’t have a good performance and I need to look back at it and assess where we should have been better.
“We’ll look for a response next week.”