Conor Gallagher and former Manchester City forward Cole Palmer put the hosts in control in the first half, before quickfire goals from Alejandro Garnacho and Bruno Fernandes hauled the Reds level heading into the interval.
A tense second half looked to have been edged by Garnacho's close-range header, from Antony's superb pass, but a second Palmer penalty of the evening and a last-gasp drive from the England international clinched the 4-3 victory for Mauricio Pochettino's men.
The immediate feelings for United will be pain and disappointment but, while the result and nature of the defeat is far from what Ten Hag will have wanted, there were still plenty of positive points arising from our trip to Stamford Bridge.