MANCHESTER, England—Ralf Rangnick is beginning to understand just how big a job he has taken on at Manchester United. His players are already becoming dispirited, too. Rangnick fell to his first loss as United manager after Joao Moutinho’s 82nd-minute strike earned Wolverhampton a 1–0 win in the English Premier League on Monday, and his team’s first victory at Old Trafford since 1980. Outplayed for much of the game, United’s players looked like they would survive for a point until Moutinho met a defensive headed clearance by controlling the ball at the edge of the area and driving in a volley that rolled just inside the post. This was the toughest test of Rangnick’s opening six matches in charge and United at times couldn’t get near Wolves, whose passing and movement was sharper in its first game in two weeks following COVID-19 issues in the squad. Wolves had 19 shots in …