The Community Shield is a curtain-raiser, but it does not always reveal an accurate picture.
The temptation is to assume that whoever end up celebrating at Wembley in August are set for a season of success.
In reality, not since 2010, when Manchester United beat Chelsea, have the victors gone on to become champions.
Yet defeat has its own perils. The last two title winners, Chelsea and Leicester, delivered mediocre displays in the Community Shield, setting the tone for underwhelming seasons.
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Chelsea were undercooked and unimpressive on this stage two years ago. Viewed with hindsight, it was the beginning of the end of Jose Mourinho's reign.
This game may not offer the right sort of omens, but it can provide the wrong kind and Antonio Conte has already spoken of his determination to avoid a "Mourinho season".
And defeat would continue an unfortunate habit for either. Arsenal have lost two of their last three pre-season games, Chelsea their last two.
The question is which of their two recent meetings provides the most accurate portents.
Arsenal were surprisingly dominant and hugely impressive, and Chelsea uncharacteristically poor, in May's FA Cup final.
There was a role reversal when the Blues won a friendly 3-0 in Beijing two weeks ago.
Yet it was notable then that Conte fielded his strongest available side, whereas Arsene Wenger did not.
The Italian may pursue revenge for the FA Cup final upset but Wenger, with six Community Shield wins, can be a specialist on such stages.
Each club are set to give a competitive debut to club-record strikers, in Arsenal's Alexandre Lacazette and Chelsea's Alvaro Morata, presenting an intriguing comparison as to who is the better buy, but neither may be accompanied by their most potent winger.
Injuries and Confederations Cup commitments affect selection. Chelsea are without Eden Hazard and new signing Tiemoue Bakayoko, while fellow newcomer Antonio Rudiger may not start and Diego Costa, long the scourge of Arsenal, is in exile.
Wenger could omit Alexis Sanchez and Shkodran Mustafi after their busy summers.
As this is a bridge between pre-season and the actual campaign, one test is if those who have excelled in the warm-ups can continue in more meaningful matches.
Willian and Michy Batshuayi, who exploited poor Arsenal defending in China, are cases in point.
And this could come down to the respective rearguards.
Arsenal's wing-backs, new signing Sead Kolasinac and Alex Oxlade-Chamberlain in particular, have been in fine form in friendly matches but their back three has looked altogether less secure than it did at Wembley in May.
Wenger prospered in his spring surge by copying Conte's 3-4-2-1 formation.
Now a reunion may be decided according to who plays the Italian's system better. Because, even if victory may not have huge consequences, defeat can reveal worrying flaws.