Arsenal are sweating on the fate of Gabriel Jesus after the striker returned to London for further tests on the knee ligament injury that ended his World Cup.
The 25-year-old was hurt during Brazil's defeat by Cameroon last week and has been seeing a specialist after returning from Qatar.
It's understood Arsenal are hopeful the damage is not too serious, with Brazil initially indicating Jesus could face three months out.
Further assessments on Tuesday should give Arsenal a clearer picture of whether the striker needs surgery.
Until then, club sources insist, it is difficult to know definitive timelines - or whether Arsenal will need to look for a replacement in the January transfer window.