Anderson drew United level
Manchester United remain top of the Premier League after beating Reading in a remarkable seven-goal thriller.
United fell behind when Hal Robson-Kanu lashed in but hit back via Anderson's finish and a Wayne Rooney penalty.
The Royals reclaimed the lead when Adam Le Fondre and Sean Morrison both headed goals from corners, reports the BBC.
The visitors swung the game their way through neat finishes from Rooney and Robin van Persie, who also had a shot that crossed the line not given.
United came into the game knowing a point would be enough to return them to the top of the Premier League table, after Manchester City's 1-1 home draw against Everton on Saturday had dislodged them for a few hours, while three points would open pre-Christmas daylight between them and their fierce rivals.
That the Red Devils achieved the latter tells only half the story of a phenomenal game of football at a ground that has already hosted its share of see-saw goalfests this season and provides more questions than answers about the overall quality of this current United side.
The first half alone was an epic, showcasing seven legitimate goals, one wrongly adjudged not to have crossed the line, appalling defending that warranted a pre-half time tactical substitution and the kind of end-to-end football used to justify the Premier League's unofficial reputation as the best league in the world.
Reading may not be taking any points but they deserve their share of the plaudits for a committed contribution to a game from which any reward would have been a bonus in their quest to extend their top-flight stay to a second season.
The most-notable examples of defensive frailty came from the title-challengers, who fell behind to the first goal for the 10th time in the league this season - when Jonny Evans' poor clearing header allowed Robson-Kanu time and space to lash in from close range - and then conspired to fall behind again midway through the half when identical Nicky Shorey corners were headed home in the box by Le Fondre and Morrison respectively.
Full-back Rafael was whipped out of the action to be replaced by Chris Smalling but in truth any one of the back five could have suffered the Brazilian's fate.
That United were not facing an uphill battle of Arsenal in the League Cup proportions owes purely to their potency at the other end of the field, where they retain the ability to carve teams open seemingly at will.
A slick one-two between Anderson and Ashley Young and a superb near-post finish from the Brazilian, followed by a calmly-converted penalty from Rooney after Jonny Evans was bundled over by Jay Tabb, overturned the Royals first goal.
And Rooney's neat side-footed goal from a Patrice Evra cross, just before Van Persie's own tidy finish following a flick from his strike-partner ensured they led at the break.
United should have had a fifth as well prior to the 45th minute when Van Persie's shot from close range crossed the line before being cleared Shaun Cummings but the officials ruled otherwise.
After a first half like that, the second was always likely to be a relative disappointment and so it proved with much fewer chances.