It's hard to know what to expect from Sporting given this is only their second game without Ruben Amorim, and their first game came against lower league opposition. Regardless, it would be unwise to expect a significant dropoff so early, and with home advantage on their side it's likely they're going to be a stuff test for Arsenal.
Since making their return to the Champions League last season, the Gunners have looked really poor when playing away from home, winning just one of six away games. Ultimately, Sporting have won 17 and drawn one of their last 18 games, and with how rocky Arsenal are away from home in this competition it's hard to be confident in them coming away with a win. Sporting CP 1-1 Arsenal.