Manchester City cruised to victory over Sunderland at the Etihad Stadium to move within two points of Arsenal at the top of the Premier League.Ruben Dias opened the scoring for City with a remarkable, Vincent Kompany-esque long range effort into the top right corner, before Josko Gvardiol doubled the lead a few minutes later with a header from a Phil Foden corner.Foden completed the scoring in the second half, heading home a delightful Rayan Cherki rabona cross to give Pep Guardiola’s side a deserved three points.Here are three things we learned as City beat the Black Cats:Cherki is electricPlenty of Manchester City players performed well against Regis le Bris’s side, but none more so than Cherki.The French attacking midfielder had big expectations essentially coming in to replace departing club legend Kevin de Bruyne, and he has surpassed them so far being the Premier League’s top assister with just 350 minutes played.Cherki is extremely creative and two footed, and always looks to progress the ball by showing for it and playing forward.Guardiola wants to stress that he isn’t the finished article yet, and didn’t seem all that impressed with his rabona cross, deeming it unnecessary and prone to making him look foolish if he misplaces it.But I think that’s mostly media talk from the City boss. He’ll know just how well the 22-year-old played and what he’s got in his locker, and I’d be surprised if he doesn’t start him at the Bernabeu on Wednesday night.Haaland being double marked is benefitting FodenJust the one goal in his last four games in the Premier League is poor going by Erling Haaland’s standards, but elsewhere, players are benefitting.Whenever City had the ball in the final third, two of Sunderland’s three centre backs stuck touch tight to Haaland, more or less marking him out of the game.But because of that, Foden, Cherki, Bernardo Silva and Jeremy Doku got lots of space in between the lines.They capitalised on it for the first goal, with Cherki being able to receive and lay off to Dias, who obviously finished extraordinarily well.For the third goal, Haaland pulled away to the back post, attracting two with him and allowing Cherki to find Foden in the box and the 25-year-old headed it beyond Robin Roefs in goal for Sunderland.It might see a temporary decline in Haaland’s remarkable scoring numbers, certainly against low block teams, but will allow the rest of City’s attackers the chance to thrive.Set piece threat is finally improvingIt’s four – yes four – Premier League games in a row now that City have scored a goal from a set piece.Dias scored against Newcastle United, before Gvardiol got City’s second goal against Leeds last week.Foden scored on the stroke of halftime against Fulham in midweek, with the corner from the left hand side finding City’s number 47 on the edge of the box, who curled it into the top left corner.This week, it was a brilliant right sided inswinging delivery from Foden that was met by a thumping Gvardiol header to once again double City’s lead like at Leeds last weekend.New set piece coach James French is clearly making his mark at City, and hopefully this is a sign of things to come with teams like Arsenal showing that it’s very possible to rely on set pieces as a regular source of goals.