After five games without a victory at Anfield, United were again struggling, even against a side reduced to ten men following the first-half dismissal of Jonjo Shelvey. And when Steven Gerrard struck straight after the interval, it seemed their unhappy recent record on Merseyside was going to be extended.
Instead, Rafael curled home a superb equaliser, which allowed United to create the platform from which Robin van Persie eventually secured maximum Premier League points with a late penalty.
"It was an important time to get the goal," said Rafael. "It was a good moment to get it because it was so quickly after they scored. If we hadn't scored then we might have got a little bit nervous."
Rafael has now scored twice this season after also finding the target against Fulham last month. It leaves him second in United's scoring charts, trailing only Van Persie, who heads the top scorer standings with five.
The defender is benefiting from his Olympic experience with Brazil earlier this year, even though he eventually had to settle for a silver medal in London. At the time he expressed a hope that Premier League crowds would start to appreciate his all-action approach.
That is certainly the case at Old Trafford now, even if some reservations have been held about his impetuous nature. Sometimes it can easily be forgotten Rafael was only 22 in July and is still making massive strides in his fledgling career.
"It's definitely the best goal I've scored for United," he said of Sunday's excellent effort, a curling left-footed strike that bounced in off the post. "I have scored four goals for United now, one with my head and two with my left foot. Maybe I am better with the left."