Monday's meeting of Labour's ruling National Executive Committee (NEC) will set the timetable for the party's leadership contest.
If that sounds like a drab technical meeting, don't be foxed.
The decisions taken by this group could influence the outcome of the contest.
First they will decide the "cut-off" period for membership.
The party's rules say that if you want to join as a full member and vote in the leadership contest, you will have at least two weeks to sign up.
But the NEC could extend this period.
That would favour a candidate such as Jess Phillips, who is urging people to "join Labour to change Labour".
In other words, she is appealing to people who may not have been comfortable with the Corbyn era.
Arguably, it might also help Wigan MP Lisa Nandy, who is expected to confirm her candidacy shortly.
She trying to build her profile and appeal to disillusioned former Labour supporters, especially in England's towns.
So these candidates would probably want as much time as possible for a recruitment campaign.
But those contenders who - according to the admittedly limited polling we have - are more popular with the current left-wing membership would benefit from a more restricted timetable.
Control of the NEC in recent years has moved to the left, so it's unlikely the committee will want to be overly helpful to, say, arch-Corbyn critic Jess Phillips.
But a restricted timetable wouldn't just potentially help Rebecca Long-Bailey, who has been dubbed by critics as a "continuity Corbyn candidate".
It would likely also favour Sir Keir Starmer, whose pro-EU referendum stance and effective Parliamentary performances seem to have, thus far, endeared him to a chunk of the largely pro-Remain membership.
The NEC will also decide the rules around the participation of "registered supporters" in the leadership election.
Under this scheme, non-party members can sign up temporarily at a reduced cost to cast a vote.
Here again, Jess Phillips will be keen to attract outsiders and former members who want the party to change direction.
In 2015, people were given two months to sign up for a small fee of £3.
In 2016, the NEC gave them just two days - and the fee went up to £25.
Remarkably, though, more people signed up in 2016 than in 2015.
So if the left-leaning NEC fears an invasion of the Centrists, it could opt to restrict the joining window to a mere porthole, and up the cost even further.
If, on the other hand, they think more people might join to keep the Corbyn flame burning, they can - if they wish - do the opposite.
Now, all this may sound desperately cynical - but last time around, when Owen Smith unsuccessfully challenged Jeremy Corbyn, a dispute over the leadership rules ended up in the courts…