I don't think Luton Town is a threat to Manchester City, I don't underestimate them, but I believe Manchester City can win when the whistle signals the start of the match. With Manchester City's current performance being strong, I believe they can win, although as you said they will probably rest their best players to face the match with Real Madrid which is indeed a big match and the one they are playing against is a strong team in their league.
But even so, I don't think Manchester City should underestimate Luton Town, because in the current season there are lots of surprises happening, which is feared that Luton Town will also give surprises, especially if Manchester City won't field their best players in this match against Luton Town. They still have to be alert, lest Luton Town give a surprise that will surprise many City fans. although there is no doubt about Manchester City's strong performance.
What a surprise as Manchester city scored their first goal on the first minutes of the match, due to the pressure that they started the game with. Haaland was the player that took the shot which was save first by the goalkeeper of Luton, and lastly the ball came back to Haaland which he took a powerful shot that was deflected by Luton player into the back net of the post.
It was just their first pass that gave them the lead, I believe that was what Luton was like preventing not to conced an early goal. The match look more easier for Manchester city than I expected. The host is on the lead with 1-0.
Manchester city is now first on the table, until when Liverpool wins their match.
with control of the ball which is dominated by Manchester City, based on statistics, Manchester City are indeed the ones who have the most power in the match, with their good performance they can be superior until the whistle marks the end of the match, with this victory Manchester City can lead the top ranking in the Premier League, I think Manchester City does have a chance to win this season, because of its good and strong performance.
with their next match against Real Madrid I hope Manchester City can win, but Real Madrid is a strong team in La Liga, because they are at the top of the rankings with points far from the other teams in La Liga. I'm not completely sure Manchester City can win, but I hope they can beat Real Madrid in the second leg. In their first match, Manchester City controlled the game better, but the end of their match was a draw, and I think they can win the next match. like beating this Luton. But of course Luton and Real Madrid cannot be compared, because Real Madrid is stronger in performance.