Steve Clarke's side have won their opening three Premier League matches at the Hawthorns and demonstrated this impressive form with a dominating first-half display against bottom-of-the-table QPR.
Morrison nearly returned the favour soon after by fizzing in a low cross for Long, but he could only direct his effort over the crossbar.
The Scotland midfielder was involved again when West Brom did double their advantage, crossing for Zoltan Gera to eventually tuck home after Anton Ferdinand miscued his clearance straight to the former Fulham man.
Adel Taarabt, who was awarded a start after a goalscoring appearance as a substitute against West Ham United on Monday, reduced the deficit with another fine individual strike.
The Moroccan controlled Esteban Granero's lofted pass on his chest before firing in a volley past Ben Foster to end West Brom's flawless home defensive record and keep the Hoops within touching distance of a result.