Jose Mourinho is - or perhaps was - the ultimate manager for a such an occasion but, just when he thought he'd got arguably the most prized and satisfying one of the lot so far, Arsene Wenger's side snatched it from his grip.
Getting beaten by City in the Manchester derby and crushed at Chelsea has undermined the process Mourinho is trying to oversee with a side that still look fragile confidence-wise.
The 0-0 stalemate with Liverpool is a feather in the side's - and Jose's cap - given how Jurgen Klopp's outfit are putting their opponents to the sword.
But we need more impressive plumage than the solitary point plundered on Merseyside and a cup win over a second-string City side - no matter how satisfying those results were.
This was the game we had identified as the fixture that could finally light the fuse, get some momentum and fire some oomph into United's campaign.
Annoyingly, we were so close to doing so.
After the curious mix of frustration and delight of the avalanche of chances in the previous two home games against Burnley and Stoke and the stroll against an abject Swansea, United had to get used to a more conservative supply of opportunities and less possession.
United got no help from referee Andre Marriner but - as annoying as that was - sometimes you need to put perceived injustices aside and take the game by the scruff of the neck.
Paul Pogba was again impressive in a midfield trio, and once the early threat of Alexis Sanchez and Mesut Ozil faded, that heavyweight-worthy scalp started to look like it was on.
Following his recent drought out on the right, there was a hope that Marcus Rashford would rediscover his goalscoring touch stationed up front in the absence of the suspended Zlatan.
Mourinho also recalled Anthony Martial on the left but his disappointing season continued with another below-par performance.
That left Rashford on his own up against an Arsenal defence far more solid than we'd expected and certainly not as vulnerable as when the academy graduate made his dramatic entrance in February.
The last time he faced Arsenal turned out to be a very good day for the homegrown youngsters, but last season's match-winner was skinned easily by Oxlade-Chamberlain to allow Arsenal their last gasp equaliser - and there was nobody at the back for the Reds to outjump Giroud and clear.
United have not won successive league games since August and let slip a major platform to end that frustration and reboot our season.