Costa would score his first league goal since his return to Benfica against C.D. Nacional in September 2007. His displays in the league would earn him the SJPF Player of the Month award for September 2007. Following qualification to the group stage, Benfica was drawn against Costa's former club Milan. The inaugural match of the group stage in September 2007 saw Benfica take on the "Rossoneri" at the San Siro, where Milan won 2–1. The return fixture on matchday 5 would see Milan visit the Estádio da Luz, where the teams drew 1–1. Benfica would exit the competition in third place behind Milan and Celtic, thereby dropping into the knockout stages of the UEFA Cup.