Erik ten Hag's reign as Manchester United manager got off to a nightmare start as Brighton registered their first ever victory at Old Trafford with a 2-1 win on the opening weekend of the Premier League season.Any hope of a fresh start for United after a miserable 2021/22 season was wiped away within 45 minutes as Pascal Gross struck twice to put Brighton in command.Alexis Mac Allister's own goal gave United a foothold in the game, but they rarely looked like getting back on level terms, showing the scale of the task lying ahead for Ten Hag.The former Ajax boss left Cristiano Ronaldo on the bench after he only returned to pre-season training last week.Ronaldo is reportedly seeking an exit from Old Trafford to play Champions League football this season.But without the five time Ballon d'Or winner, United had no focal point to their attack as Christian Eriksen started in an unfamiliar role as a false nine.The outcome could have been very different had Bruno Fernandes not blazed over a glorious chance on six minutes.The nadir of a nightmare campaign for United last season as they finished sixth in the Premier League came in a 4-0 defeat to Brighton in May, and the Seagulls quickly settled into their passing rhythm.Graham Potter's men have lost two of their best players during the transfer window, as Yves Bissouma joined Spurs and Marc Cucurella moved to Chelsea this week for a club record fee in excess of 60 million ($72 million).But it did not show as Brighton exposed the same flaws in United's wide open midfield to pick apart Ten Hag's men with ease.Danny Welbeck, who United discarded back in 2014, was a constant threat in behind the vulnerable defensive pairing of Harry Maguire and Lisandro Martinez.Welbeck created the