Sporting fan here and wanted to give a bit of context into the team you are facing as I ran across a little bit of misinformation.
First of, obviously City are one of the teams we didn't want along with Bayern and Liverpool. Anything that isn't a City win in both games would be a surprise, however I reckon this Sporting team may cause some concerns and it probably won't be the 9 or 10 goal aggregate some fancy here. It may obviously happen, on a good day City is capable of doing that to just about anyone but don't be surprised if it is a little closer than you might anticipate.
Basically, the team lines up in a 3-4-3 and is incredibly compact defensively and quite tough to beat. This year, they have only conceded 5 goals in the league (3 of them coming from Benfica, Porto and Braga, the other top 4 teams in the league) and are still unbeaten domestically. Last year they went the first 32 games (when crowned champions) unbeaten having only conceded 15 goals in that span. They normally lineup defensively in a 5-2-3 and rarely give up on the front three pressing the defense, which can create problems having only 2 in the middle against City's midfield. Against Dortmund away, the team went to a 5-4-1 to protect themselves a bit more, especially because of the heavy defeat against Ajax in GW1. The team is quite versatile, they dominate games in Portugal (efficiency has been lacking to get more goals however) with a high press but they can also be very compact while lining up in a low block (watch out for the offside trap using the penalty area line as a reference) and that is what will probably happen against you lot. Coates is the stalwart leader and captain in the back 3, great in the air and imposing presence. Gonçalo Inácio is a young prospect with great on ball ability but still lacks some strength (think young John Stones with a left foot or maybe a less physical Laporte). Porro (loaned by you) has shown the ability that mad y'all buy him. Great offensively, stamina for days but still improving defensively.
Offensively, we obviously have to dominate in Portugal with possession, but this team has an incredible ability to be deadly on counters and that's what you'll see since you will have most of the ball. Don't expect it to be Adama Traores upfront, the front three (Sarabia, Gonçalves and Paulinho) aren't the fastest you'll see but their definition and quick combinations and sense of timing to find the open space is spot on. Pedro Gonçalves (or Pote) scores goals for fun and is the biggest threat. Paulinho usually has a Firmino type role in dropping deep and setting the other two up with combinations in build up. Sarabia is a very classy and tecnhical player, formerly of PSG and Sevilla. The midfield is usually Palhinha and Matheus Nunes (keep an eye on him) and phisycally, I'd say they're a Premier League duo which is rare here in Portugal. Palhinha is a CDM with great physicality and stamina. Covers so much ground, is strong and very good in duels and tackling. Nunes is a box to box with an absurd acceleration and speed (check the Benfica 1-3 win highlights). He struggles a bit against low blocks but with space he is absurd with his technical ability and abilty to break opposing lines by carrying the ball.
I guess you are wondering I'm probably overselling this team, but they lost 1 game in the league (and it didn't matter, it was after having won it) in 1 and half seasons, while also taking a cup and supercup.
The games against Ajax as I have seen mentioned need a bit of context. This is a very young team with little to no experience in Europe (much less in the Champions League) and the first match of the groupstage was against Ajax. We had no Pedro Gonçalves (biggest ofensive threat), Coates (leader and captain of the back 3), Sarabia had joined a couple days earlier and didn't start and Inácio (second best center back) left the game injured 20 minutes into it. That's a lot of casualties for a young team with no experience in their first game. And the nature of the game just fell into Ajax. Everything went in basically and the team was just lost defensively with a back 5 with no experience playing together and with full backs at center back. Despite that, after half time we got to 3-2 but that goal was disallowed by inches and the next attack they had got them to 4-1. A bit of an unfortunate game and an outlier. The last game against Ajax, we simply rotated the squad and played with our subs, including 18, 17 and 16 year old players against their starters. Normal outcome, we have a small squad and can't afford to get them more fatigued or injured.
Hope you enjoyed it and hope we have 2 fun games. Hopefully with the same result that we had in 11/12 :)
Any questions, feel free to ask.