Wayne Rooney scored twice as Manchester United moved three points clear at the top of the Premier League with an astonishing 4-3 win at Reading's Madejski Stadium.
United have made a habit of falling behind this season, and this frantic first half provided another glimpse of their frailties in dealing with cross balls as they shipped three goals in 23 minutes yet still led at half-time.
They trailed for the 14th time in 22 matches this season when Hal Robson-Kanu whacked a volley high into the net on eight minutes after Jonny Evans had knocked a Jobi McAnuff cross back into the traffic.
Despite never managing to find their fluent best form, United rallied to lead 2-1 courtesy of an Anderson goal on 13 minutes that he buried with some venom and a composed Wayne Rooney penalty three minutes later after Jay Tabb had clumsily barged Jonny Evans off the ball in his own box.
But the visiting side continued to toil in defence as Adam Le Fondre (19) and Sean Morrison (23) benefited from some wretched marking to give the home side an unlikely lead midway through the first period. Both came from Nicky Shorey corner kicks as United's defence was posted missed only a few yards from their own goal.
Goalkeeper Anders Lindegaard also endured a personal nightmare as he continually failed to come off his line causing scenes of widespread panic between Rio Ferdinand and Evans at the heart of the visiting defence.
Despite their obvious shortcomings, United were easy on the eye during their forays forward and scored their goals almost at will that proved to be decisive with Rooney converting Patrice Evra's cutback for the equaliser on 30 minutes.
Robin van Persie came up with the winning goal on 34 minutes when he coolly finished off a Rooney flick from a Michael Carrick pass. It said enough about the nature of the performance that United barely looked happy with their own goals.
Van Persie joins Luis Suarez and Michu on 10 goals at the top of the Premier League scoring charts, but could and should have had two more.
The referee Mark Halsey and his match officials made an awful mistake when Van Persie rammed the ball over the line on 38 minutes after Chris Smalling - who enjoyed a commanding performance after replacing the poor Rafael on 31 minutes - saw a header clawed out by goalkeeper Adam Federici.
The ball broke to the Dutch striker whose finish was clearly over the line from close range as Adrian Mariappa somehow scrambled the ball clear on 38 minutes. Astonishingly, the referee waved play on with both his assistants missing it in a moment that will prompt further debate over the introduction of goal-line technology.
Van Persie also looked certain to hand United a 5-3 lead on 65 minutes when he picked the pocket of the slipshod Federici but lost his balance in clipping the ball wide of the target from six yards out.
In the end, it mattered little to the final outcome as United held on fairly comfortably.
It is over six years since Manchester United last conceded four goals in a Premier League away match – the 4-3 defeat at Blackburn in February 2006. The main statistic is winning the game.
But Sir Alex Ferguson is well aware that his side will have to improve in defence when they visit Premier League champions Manchester City at the Etihad Stadium next Sunday.
Life could be worse. At least Ferguson is not faced with Brian McDermott's issues as he watched his Reading side slump to a third straight defeat. They remain second bottom of the Premier League table, three points clear of Queens Park Rangers.
MAN OF THE MATCH
Wayne Rooney (Manchester United): Scored twice and also set up Van Persie for his goal to help out on a day the United defence will not wish remember with any great pleasure.
Reading: Federici 4, Cummings 5, Shorey 6, Mariappa 6, Morrison 6; Leigertwood 6, Tabb 6, McAnuff 6, Robson-Kanu 7; Le Fondre 7, Roberts 6..subs: McCleary 6, Hunt 6, Pogrebnyak 6
Manchester United: Lindegaard 4; Rafael 4, Evra 6, Evans 5, Ferdinand 5; Anderson 6, Carrick 6, Fletcher 6, Young 6; Rooney 8, Van Persie 6..subs: Jones 6, Smalling 7, Welbeck 6