Harry Maguire felt Manchester Uniteds poor ball retention and weak mentality were crucial factors in their chastening 2-1 defeat to Brighton and Hove Albion in Erik ten Hags first Premier League match in charge.United were beginning a new era at Old Trafford on Sunday, and Brighton were seen by many as a kind first opponent despite the Seagulls battering them 4-0 in May.Ten Hag handed debuts to Lisandro Martinez and Christian Eriksen, but with Anthony Martial injured and Cristiano Ronaldo only deemed fit enough to start Zach Ertz Jersey on the bench, United lacked a presence in attack.Two close-range goals from Pascal Gro s had Brighton 2-0 up at half-time, and although a slightly improved United performance led to a scrappy Alexis Mac Allister own goal, the Red Devils could not come up withan equaliser.In the long run it is hoped Ten Hag will be able to implement an attack-minded po se sion-based brand of football, but there were few signs of it on display here.Scott McTominay was indicative of Uniteds poor ball retention and lack of control, completing Herman Edwards Jersey just 19 pa ses at a succe s rate of 67.9 per cent despite playing nearly the entire match in midfield. Even goalkeeper David de Gea attempted (29) more pa ses than the Scotland international (28).Captain Maguire thoughtUnited showed apoor response to going behind.He told Sky Sports: I think we started pretty the game well and on the front foot and as a team we had control of the game.Then we conceded the first goal and that knocked back really badly. We stopped playing from then, they got a lot of control in the game.We need to look at not letting that first goal set us back as much as it did, but weve got to be better on the ball, we gave the ball away too often in that first half especially after the first goal, we gave them encouragement to come forward and attack us. It was a nightmare start to be 2-0 Harold Carmichael Jersey down at half-time. Everyone knew the task. We had a bad season last season, now weve got a new manager trying to put his philosophy on the team, but when we dont get it right we look far too open.Specifically on the subject of United failing to react to Brightons first goal, Maguire added: Its something we need to Wendell Smallwood Jersey addre s or itll keep happening.The first goal felt like a big blow to all 11 of our players. We spoke about getting the next goal at half-time .I think in the second half you saw good parts to our game, but overall we didnt do enough. We had a lot of pre sure and a lot of ball, but we need to be a bit more creative and we need to improve on that.It was the first competitive game Maguire had played with new signing Martinez, and while the Argentina international showed glimpses of his ability, Danny Welbeck Wes Hopkins Jersey got a lot of joy out of both centre-backs.Maguire accepts forging a proper partnership will require patience.Its great to have Licha Martinez at the club. We have competition for places at centre-back, he said.Weve not played much together and in that first period we werent on the same wavelength. Centre-back partnerships are built over time and we will get a lot better and keep clean sheets.