Ole Gunnar Solskjaer was left with plenty to ponder as Manchester United were beaten 4-2 by Championship club Queens Park Rangers on Saturday afternoon.
While it was far from a full-strength United team, with plenty of their stars yet to return from their holidays after Euro 2020, it was a result and performance to suggest worries over a lack of squad depth haven't gone away.
There were some positives, such as Jesse Lingard's early goal and the performance of Facundo Pellistri, but the way United's youthful back line allowed QPR to score three times in seven minutes early in the second-half was alarming.
On the day Solskjaer signed a contract extension until 2024, it was a reminder that nothing can be taken for granted ahead of the new season.
We take a look at five talking points from the Kiyan Prince Foundation Stadium.
It was an afternoon to remember for Queens Park Rangers as they defeated Manchester United 4-2 at the Kiyan Prince Foundation Stadium on Saturday afternoon
A dejected Jesse Lingard and Juan Mata kick off after one of the QPR goals in the second-half
Steep learning curve for young defensive duo
It was a nightmare afternoon for United's young central defensive pairing of Axel Tuanzebe and Teden Mengi as QPR's forward ran them ragged.
In fact, you can bundle both Aaron Wan-Bissaka and Brandon Williams into that shambolic display at the back because they all looked significantly off the pace.
There are high hopes at United for Mengi, 19, who signed a new contract until 2024 during a loan spell at Derby towards the end of last season and he's been involved with Solskjaer's squad for some time.
Teden Mengi suffered a chastening afternoon as QPR's strikers caused plenty of problems
But he was given a real schooling here, not least when leaving Charlie Austin completely unmarked for QPR's equalising goal after seven minutes.
Austin is a wily customer but United left the back door open and Lee Wallace's cross picked him out in acres of space at the back post.
Tuanzebe, 23, appeared in 19 matches for United last season and has been around the scene for a couple of years now since his loan spells at Aston Villa.
The highlight was his display in the Champions League win away to Paris Saint-Germain last October but many remain unconvinced by him.
Axel Tuanzebe attempts to keep tabs on QPR's Ilias Chair as Facundo Pellistri watches on
Brandon Williams is kept at arm's length by Albert Adomah on a difficult afternoon for United
He certainly struggled to get a grip on proceedings here and was too slow getting out to Lyndon Dykes when he scored QPR's second shortly after the break. Dykes had all the time in the world to get his shot away.
Neither suggested they're going to be pushing to become Harry Maguire's regular centre-half partner in the season ahead.
Wan-Bissaka struggled in the first half to keep tabs on Wallace and the slippery Ilias Chair, while Williams' poor challenge allowed Dykes through to fire home the fourth goal.
United's defenders - and Pereira - stand off Moses Odubajo as he fires home QPR's third goal
Lingard offers a timely reminder of his quality
It didn't take too long for Jesse Lingard to open the scoring and he seems to be carrying on the fine form from that West Ham loan spell that resuscitated his career.
It was a well-taken goal and well-timed as United prepare to make a decision on Lingard's future.
There is no shortage of interest in him - from West Ham and reportedly also Everton, Leicester and Atletico Madrid.
Jesse Lingard celebrates opening the scoring for Manchester United three minutes in
Now the confidence has been restored to Lingard's game, he'll clearly be an asset to anyone in the Premier League even if there's clearly no room for him to play regularly at Old Trafford.
There would have been plenty of scouts keeping tabs on Lingard in this game and he did himself plenty of favours with the early goal and a couple of other breaks afterwards.
Although he would have loved to have been part of England's Euro 2020 campaign, it might prove a blessing in disguise to get a full pre-season under his belt.
Lingard, on this evidence, will hit the ground running when the new season starts - wherever he ends up playing.
Lingard was in impressive form in his 62 minutes of football as interest in signing him grows
Electric Pellistri deserves a chance
