Alex Mowatt's brace, after Josh Maja opened the scoring inside the first minute, sent West Brom top of the Championship with a clinical 3-0 victory over winless Portsmouth.
The in-form Maja bagged his fifth goal of the season to give the Baggies the perfect start by firing home Tom Fellows' cross.
Albion started quickly again in the second half and got their second goal when Mowatt calmly found the top corner.
Mowatt then added gloss to the scoreline with a brilliant free-kick in stoppage time.
Carlos Corberan's unbeaten side move one point clear of Sunderland at the summit after five games.
Pompey, by contrast, are second bottom after a tough start to their return to the second tier.