After Stefanos Tsitsipas' victory in three sets against Andrey Rublev, which qualifies Dominic Thiem for the semi-finals of the ATP Finals and eliminates the Russian, the accounts are very clear for Rafa Nadal regarding your options of being at the crossroads.
There is only one possibility that this will happen for the sixth time in the Spaniard's career: Nadal goes to the semifinals if he beats Tsitsipas on Thursday (9pm). He would enter as second in the group even if Thiem loses against Rublev, because in the tie at two wins, the Austrian prevails by having beaten the Spanish on Tuesday. Defeat would send the world's number two home.
The classification would be like this if the Balearic wins:
1st Thiem 3-0 or 2-1
2nd Nadal 2-1
3rd Tsitsipas 1-2
4th Rublev 0-3 or 1-2