For Louis van Gaal and Arsene Wenger alike, the final reckoning awaits.
For the Manchester United manager, opportunities to show he should keep his job are running out.
For his Arsenal counterpart, the prospect of a first league title in 12 years depends largely on five away days. This is the first of them and Arsenal visit Tottenham on Saturday. Later trips to Everton, Crystal Palace and Manchester City assume a similar significance.
Collect too few points on the road and they will not be champions, but a victory today would put Arsenal 13 points ahead of United and perhaps end van Gaal's chance of a top-four finish.
Arsenal were tormented by Lionel Messi on Tuesday, but this could be messy for United.
Wins offer the prospect of a reward for Wenger. For van Gaal, routs against Shrewsbury and Midtjylland merely delayed the day of reckoning.
If executive vice-chairman Ed Woodward has remained an ally, other minds are made up: The fan base and many within the club have lost faith in the Dutchman.
United's slump dates back to October, when he got his tactics spectacularly wrong at the Emirates by attempting a pressing game and seeing his team out-passed, outrun and outwitted.
That 3-0 win remains the high point of Arsenal's domestic campaign. While they overcame league leaders Leicester two weeks ago, van Gaal's team have not defeated top-four opponents since the opening day.
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They require a landmark result and a clean bill of health.
But injury-hit United find themselves short-staffed. They are waiting to see if Anthony Martial and David de Gea, two shining lights in the darkest of seasons, will be fit.
The chances are both will start, the Spaniard behind officially the most frugal home defence in the division. But they are a makeshift back four and Arsenal should sense they can exploit that.
It gives a team with too little sharpness in attack and without a goal in two games an added incentive to advance.
It will be instructive if Wenger benches Olivier Giroud, who has not scored in eight, to recall the United old boy Danny Welbeck, who scored the goal that knocked his former club out of the FA Cup last season.
Welbeck's dramatic injury-time winner against Leicester two weeks ago has the potential to prove the turning point in their season.
Van Gaal's United are notoriously slow starters at Old Trafford, which should give Arsenal time to get into their stride. Wenger's men looked like champions when they surged into a three-goal lead in 20 minutes in their October onslaught.
They rarely have since, while United's problems have mushroomed.
Now, with Arsenal heading out of the Champions League and United unlikely to return to it, seasons, destinies and reigns are on the line.
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