Jose Mourinho was irritated a couple of weeks ago. He disagreed with the idea that Manchester United had benefited from an easy start.
Yet if the fixture list initially favoured them, it does not now. They have Liverpool, Tottenham and Chelsea in the space of four league games.
Their title credentials will be properly examined over the next month.
Jurgen Klopp, too, has also been irritated of late. Liverpool's outstanding August gave way to a September struggle. Whereas United head to Anfield with six successive wins, Liverpool have only won one of their last seven games.
In that time, they have had 143 shots and scored just eight goals. While they have not been clinical enough in one box, they have been too careless in the other.
So enemies are opposites. United have shown a ruthlessness. Liverpool have lacked it.
Yet if that makes Mourinho's men favourites, recent history suggests otherwise. Liverpool have been the big-game specialists.
Klopp's charges were thrashed 5-0 by Manchester City last month, but have only lost one of their last 16 league meetings against the big seven. United scored a solitary goal away at the top six last season and took just two points. One came at Anfield in a stalemate when Mourinho was ultra-defensive.
It will be intriguing if he is as cautious again; perhaps Liverpool's indifferent form will encourage him to be bolder. Perhaps he will be forced to field more attackers.
Yet Liverpool's creaking rearguard can be targeted in typical Mourinho style by sitting deeper, sacrificing the slow Juan Mata and using the pace of Romelu Lukaku and Marcus Rashford to expose Klopp's high defensive line on the counter-attack.
If the assumption was that Mourinho would revert to 4-3-3 for the tougher tests, the injuries that have ruled out Paul Pogba and Marouane Fellaini may result in a change of plan.
If he deems 4-2-3-1 too progressive, he could use 3-4-3, but teams that have picked a back three against Liverpool have suffered, as Arsenal and Hoffenheim can testify.
This could be determined by tactics or by absentees. United are without two of their tallest players, Liverpool their quickest.
Sadio Mane's hamstring problem removes their most devastating attacker; without him, the supposed "Fab Four" will be reduced to three, with Philippe Coutinho shifted forward into the front trio.
But this can be a game where form is irrelevant. Liverpool tend to raise their game against the best. United have proved they can excel against the rest.
Liverpool's 4-0 demolition of Arsenal was arguably the performance of the season, but United have demonstrated the relentless consistency of potential champions.
So, one way or another, frustration beckons for either Mourinho or Klopp.
LIVERPOOL V MAN UNITED
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TEXT: RICHARD JOLLY PHOTOS: REUTERS, AGENCE FRANCE-PRESSE