The England centre-back netted his first Premier League goal for United against Chelsea on Monday night and Laurence Maguire has since revealed an eerily accurate prediction made by his older brother ahead of the match.
Ole Gunnar Solskjaer's side led 1-0 in the 66th minute at Stamford Bridge thanks to Anthony Martial's glancing header on the stroke of half-time when Maguire rose to powerfully turn home a corner from January arrival Bruno Fernandes and ultimately seal a crucial 2-0 win that narrowed the gap to the top four to just three points.
It was the 26-year-old's second goal in United colours after he notched the opener in a 6-0 FA Cup fourth-round demolition of Tranmere Rovers last month.
And sibling Laurence - himself a professional footballer at fifth-tier Chesterfield - subsequently showed that Maguire had called his effort against Chelsea ahead of time.
"The boy said he would score tonight," he wrote on Twitter above a screenshot of a text conversation between the two brothers.
"Set plays every chance for you tonight," Laurence had written.
Harry replied: "Yes I'm going to score around [sic] back tonight. Watch. I[n] swinging corner."
United's official account later retweeted Laurence with the words: "Mystic Maguire".
Many - including Chelsea manager Frank Lampard - feel that Maguire was lucky to even be on the pitch to score such an important goal.
The former Leicester defender avoided a red card in the first half after extending his leg towards Michy Batshuayi after a challenge and catching the Chelsea striker in the groin with his foot.
Maguire insisted afterwards that there was no kick out or malicious intent behind the action and was merely a natural reaction as he tried to stop the player from falling on top of him.