Alcaraz as per the tournament organisers withdrew from the tournament which takes place between October 21-29. According to notes from his doctor, he is suffering from inflammation on the sole of his left foot. As well as problems in his gluteal muscles.
Home hero Stan Wawrinka will instead take his spot in the draw due to the change in entry list, with Leandro Riedi now receiving the wildcard left free from the Swiss.
This makes Alcaraz's slim hopes of finishing as year-end No.1 just that, with Alcaraz aiming to play in Basel to close the gap ahead of the Paris Masters and ATP Finals which will now be his likely endpoint.
Reports earlier in the week prompted that he was unlikely to play Basel, with a break mooted for the next few days at least. But this will extend to a few weeks likely to get rid of niggling injuries. This though hands Novak Djokovic the advantage going into the final tournaments.