Arsenal vs Sporting CP looks tighter on the football side than a simple home-favourite price suggests. Arsenal have the edge of playing in London, defend with real authority in this competition and usually create enough pressure at home to control long stretches. Sporting CP, though, arrive in strong form, carry serious attacking threat and have enough quality in transition to make this uncomfortable whenever Arsenal overcommit.
The most likely script is Arsenal having more territory and structure, while Sporting remain dangerous enough to create their own moments and keep the match alive deep into the night. That leaves the home side slightly in front overall, but not by a margin that removes the risk of a competitive, goal-capable contest.