Manchester United suffered their second defeat of pre-season on Saturday night as they were beaten 2-1 by Arsenal in Los Angeles.
Things started off positively for Erik ten Hag when Rasmus Hojlund made the most of some poor defending to fire United in front at SoFi Stadium.
But United's defensive frailties were exposed by the Gunners. Gabriel Jesus leveled things up just before the break and then Gabriel Martinelli grabbed the winner later on.
Here, Mail Sport takes you through five things we learned…
Gabriel Martinelli scored the winner as Arsenal beat Manchester United 2-1 in Los Angeles
Recurring injury nightmare for United
If Manchester United were hoping the injury nightmare of last season was a thing of the past, they took a depressing step backwards in a 2-1 defeat to Arsenal at the SoFi Stadium.
Rasmus Hojlund and new £59million signing Leny Yoro both limped off before half-time to hand manager Erik ten Hag a painful double blow.
Hojlund went down with what appeared to be a hamstring injury five minutes after firing United in front, and walked gingerly around the perimeter of the pitch towards the dressing-room following treatment.
Yoro also seemed to know instantly that something was seriously wrong when he went down on his haunches just after the half hour mark. The young Frenchman, who completed his move from Lille just in time to come out on tour, wasn't taking any risks either and went straight off.
Ten Hag was asked about last season's injury problems in his pre-match press conference and referred to the appointment of club doctor Gary O'Driscoll 10 months ago and head physio Jordan Reece, both from Arsenal, as reasons to be optimistic.
'Now he can start fresh and be in the lead,' said the United manager. 'We also changed strategies in medical and performance to improve.' Only 24 hours later, United were facing some familiar old problems.
Rasmus Hojlund and Leny Yoro both came off injured during the first half at SoFi Stadium
Hojlund gives Heaven hell
Hojlund only lasted a quarter of an hour of United's first tour game, but the Dane made a big impression by scoring United's first goal.
He showed real strength in the 10th minute to bulldoze his way past Arsenal defender Ayden Heaven before burying his shot under goalkeeper Karl Hein.
United need a big season from Hojlund whose first year at Old Trafford caught fire around Christmas following a £73m move from Atalanta last summer but tailed off towards the end with Erik ten Hag opting for Bruno Fernandes as a false nine in the last few Premier League games and FA Cup final win over Manchester City.
He will need some support from new £36.5m striker Joshua Zirkzee with young Ethan Wheatley also emerging as an option. Ten Hag spoke about the importance of strength in depth on Friday and it was interesting that midfielder Hannibal Mejbri replaced Hojlund in the first half here.
United had Wheatley, Jadon Sancho and Antony on the bench, but Ten Hag had planned to use them in the second half and didn't want to risk overloading them by playing them for an extra half an hour.
Hojlund only lasted a quarter of an hour but the Dane made a big impression by scoring first
Leny needs time to learn
Leny Yoro will need time to adapt to English football despite his huge reputation around Europe.
The young Frenchman arrived at United from Lille this summer as one of the brightest defensive prospects on the continent, and he oozed class on his debut against Rangers last weekend. But he also made some basic errors and there was further evidence here that he is on a learning curve before he went off injured in the 33rd minute.
There were only a few seconds on the clock when his mistake let in Gabriel Jesus, but Yoro had the speed and agility to make up for his error – just as he did against Rangers at Murrayfield. Then shortly before going off, he played himself into trouble close to halfway by being too elaborate and almost had his pocket picked by Jesus.
He will be a big asset for United going forward, but fans may have to be a little patient while he adapts to a new country and league.
United fans may have to be a little patient while Yoro adapts to a new country and league
Onana spot on for Utd
Andre Onana had a difficult start to his United career when he was lobbed from the centre-circle by Florian Sotocas against Lens in his Old Trafford debut last August.
It knocked the Cameroonian's confidence for a while before he recovered to be a key performer under Erik ten Hag following a £47.3m move from Inter Milan.
A year on, Onana is significantly more comfortable as United's No. 1 and he produced an assured performance in the SoFi Stadium. The highlight was a brilliant reflex save from Leandro Trossard in the second half, Onana having made another excellent stop from Ethan Nwaneri in the first half when the Arsenal man was offside.
There was very little he could do about the Gunners' equaliser in the 10th minute when Gabriel Jesus got away from Harry Amass to score at the far post, or when Gabriel Martinelli took advantage of weak challenges from James Scanlon and Will Fish to score the winner.
But he came up trumps in a pre-agreed penalty shootout to make saves from Kai Havertz and Jakub Kiwior, and give United some consolation from this all-English affair.
Onana is now comfortable as United's No. 1 and produced an assured performance in LA
Antony and Sancho fall flat
It's a sign of where they sit in the pecking order that Antony and Jadon Sancho started this match on the bench with Amad Diallo – who was United's man of the match against Rangers a week ago – picked on the right wing.
With combined transfer fees of £159m, neither player has come close to living up to expectation at United and both could be sold this summer if the right offer comes in.
Both Antony and Jadon Sancho (pictured) struggled to have any influence on the game
Neither made much of an impact in Los Angeles as Antony made his first appearance of pre-season on the right wing and Sancho his second on the left in the second half.
The stage was set for them to stake their claim for a place in Ten Hag's starting XI for the game against Liverpool in Columbia, South Carolina, assuming the United boss plays a younger side against Real Betis in San Diego. At least Sancho scored the decisive penalty in the shootout.
But this was another opportunity missed and at this rate neither will start in the Community Shield against Manchester City on August 10, even though Alejandro Garnacho may not be available after returning late to training after the Copa America.