Erling Haaland’s early goal was enough for Manchester City to overcome Brentford and head into the second international break of the season three points off the top of the Premier League.The 25-year-old’s ninth minute goal came after he outmuscled Sepp van de Berg following a long ball forward and manoeuvred the ball onto his left foot, before firing into the bottom left corner for his 18th goal this season for club and country.But it wasn’t all good for City. The second half was significantly worse than the first, with goalkeeper Gianluigi Donnarumma bailing the Blues out with an excellent one vs one save from Brentford striker Igor Thiago, and Rodri being replaced with what appears to be a hamstring injury in the first half.Here are three things we learned from victory in London:Rodri was indeed rushed back too quicklyI was calling this after the midweek game when Rodri was hauled off on 60 minutes looking both exhausted and disheartened – he’s been asked to do too much too quickly in regards to playing after his injury.The Spaniard tore his anterior cruciate ligament (ACL) just over a year ago, missing almost the entirety of last season.He’s now suffered two injury setbacks – one at the Club World Cup, and one yesterday, both of which were in his hamstring.Rodri also missed the 5-1 win at home to Burnley last week, due to pain in the same knee he injured last year. He started just four days later against Monaco and then again against Brentford, before coming off before half time after clutching the back of his leg.I know it’s difficult to tell an ambitious, competitive warrior like Rodri to take a back seat when he wants to help the team, but Pep Guardiola and the medical staff need to pull rank.Nico Gonzalez is doing a good job deputising for him, meaning there’s no reason at all for the 29-year-old to be forced in as often as he is.Thankfully, Rodri said after the game that he doesn’t think it’s too serious, and whilst he says he’ll miss international duty with Spain he’s hoping to be fit for the game against Everton in just under two weeks time.Hopefully this will be nothing more than a major scare, but it indicates that City need to take better care of the 2024 Ballon D’or winner before his career at the very top level withers away before him.City must improve across 90 minsYesterday’s game showed that City are, in my opinion, not back to their best or quite ready to launch a proper title challenge in their current state.They haven’t played a good, dominant full 90 minutes this season in the Premier League since the opening day against Wolves. Against Brighton, Brentford and to a lesser extent Manchester United, they tailed off in the second half. They were made to pay against the Seagulls, and were perhaps fortunate to come away with a win against Brentford. And even United had a huge chance excellently saved by Donnarumma with the score at 2-0; had that gone it, it could potentially have been a different result.Against Burnley they had a poor thirty minutes in the middle of the game, whilst the Tottenham match was really lacklustre from beginning to end.The Brentford game I think was largely down to the home side’s improvement at half time. It’s undeniable that City were crisper and more threatening in the first half, but the Bees were really timid and wasteful whenever they had the ball.But in the second period they played menacing long balls forward to pin City back, got into dangerous wide positions and won the ball back much quicker than they did in the first half.Though it’s important to note to City’s credit that other than Thiago’s chance, Brentford didn’t really have any notable scoring opportunities.Matheus Nunes, Ruben Dias, Josko Gvardiol and Nico O’Reilly all had excellent games, and kept Keith Andrews’ side at bay. When they were breached, Donnarumma was there, safe and reliable as ever.But against stronger opposition they probably would’ve been breached more often and drawn or lost, and that’s where City need to improve in order to get back to their absolute best again.We now have a match winning goalkeeperBuilding on from what was said above, Donnarumma can now be one of a few players who can win a game for City, along with Haaland, Rodri and Phil Foden on his day.The 26-year-old’s signing was initially controversial, with many City fans – myself included – dubious that he’d actually make much of a difference due to his lack of ability on the ball.With the greatest of respect to Joe Hart and Ederson, who were unbelievable servants for City and contributed greatly to many trophies, Donnarumma seems to be up another level from them with his shot stopping, presence and control of his penalty box.Thiago should’ve scored the chance he had, but the Italian did everything right to put him off; stayed big, waited for a dodgy touch, then rapidly closed down the angle and pounced at his feet, deflecting the ball away with his chest.It’s safe to say Donnarumma has had an unbelievable start at City, coming in to be the best goalkeeper in the league and even allowing City to concede a few more chances, knowing they’ve got an extremely reliable pair of hands behind the defence.