The Red Devils’ sixth and final fixture of the summer saw a mixture of youngsters and those lacking match fitness take to the field, with all 11 of the team that started on Saturday not involved at Old Trafford against Rayo.
Cristiano Ronaldo was one of those who did play, however, accumulating his first minutes of pre-season, while Christian Eriksen and Lisandro Martinez both started for the first time in a red jersey at Old Trafford.
But it was Amad who netted the solitary United goal of the game, minutes after replacing Ronaldo at the break, with Alvaro Garcia equalising soon after for the visitors.
But with the game only being shown live on MUTV, fans may have missed some of the more nuanced moments, and we’ve picked out five things which may have passed you by.
Who wasn’t involved?
Aaron Wan-Bissaka, Luke Shaw, Jadon Sancho and Brandon Williams didn’t feature against the side from Madrid, with United saying the quartet were all ill.
However, the latter was among several first-team stars who sat in the directors’ box watching proceedings. David de Gea, Diogo Dalot, Tyrell Malacia, Scott McTominay, Bruno Fernandes, Anthony Elanga, Facundo Pellistri, Marcus Rashford and Anthony Martial were all visible from the press box.
Several stopped to sign shirts and take photos with supporters, with De Gea and Martial spending a significant period at the start of the second period interacting with spectators.
McTominay also enjoyed a nice moment when a particularly excitable fan spotted the Scotland international. He responded by nodding, smiling and waving to the pleasantries which were directed his way.
Other notable observers included Sir Alex Ferguson and Robbie Savage, with the latter’s son an unused substitute. Coleen Rooney was also in attendance at the end of a busy week for her family.
Ten Hag welcomed to Old Trafford
Sunday was Ten Hag’s maiden game in charge at Old Trafford, and therefore a first opportunity for him to interact with the club’s home fans.
Ahead of the game, the Dutchman walked out of the tunnel and clapped the adoring fans inside the group.
It was a particularly vocal reception for the former Ajax boss, who acknowledged it in his post-match interview with MUTV.
There was an unsavoury moment towards the end of the first half when a small group of Rayo fans set off an enormous flare in the corner usually designated for away fans.
However, given it was a friendly, there were only around 30 in that particular contingency, with United supporters sitting in the vicinity.
The locals were understandably irate at the red plumes of smoke wafting over them, and from the press box, children were visibly being moved out of the way.
The flare was eventually extinguished, not after police were seen wrestling a banner away from the Rayo fans in question, which ripped in their efforts to keep hold.
The 30 or so fans were spotted leaving at half-time, with security believed to have moved them on.
Ten Hag described Martinez as a ‘warrior’ when he signed the Argentina centre-back from Ajax, and from an hour at Old Trafford it seems an apt description.
The 24-year-old, diminutive for a Premier League centre-back, didn’t hold back when it came to challenges and at one point earned a huge cheer for a strong tackle on Isi Palazon, perhaps Rayo’s best player on the day.
Martinez scrapped and battled despite the game’s lack of importance, in an approach not too dissimilar to fellow countryman Carlos Tevez from his time at United.
Returning Red Devil
Most of those who lined up for Rayo were unknown to followers of English football, but all were familiar with the man up front for the visitors: Radamel Falcao.
The Colombian played 29 times for United in 2014/15, scoring four in that period, and nearly netted again at Old Trafford on Sunday when his curling shot from outside the box smashed off the crossbar.
Falcao didn’t get a particularly warm reception from the home fans - in fact, it was no different to any other Rayo player - but he did stop after the game and pose for photos with United supporters.