Roger Federer's class shone like a beacon over the murky waters of round-robin tennis with a 6-3 6-2 defeat of Kei Nishikori at the ATP World Tour Finals before Andy Murray stayed afloat by defeating Milos Raonic.
The 33-year-old Swiss maestro, bidding for a seventh title at the ATP's year-ending shootout, oozed confidence as he racked up his second consecutive victory in Group B.
However, Murray's 6-3, 7-5 defeat of big-serving Raonic means that all scenarios are still possible going into Thursday's matches when group leader Federer faces Murray and winless Raonic takes on Asian trailblazer Nishikori.
Home favourite Murray, beaten by Nishikori on Sunday, had the added pressure of knowing that defeat to Raonic would have eliminated him but the world number six delighted a capacity crowd in the O2 Arena with a steadfast display.
Should Federer win a set against Murray on Thursday he will definitely progress to the semi-finals while Murray needs a straight sets victory to be all but guaranteed a last-four slot.
Nishikori, Asia's first qualifier for the prestige event, would also be well-placed if he beats Raonic with ease, while Canadian Raonic needs a straight sets win to stand any chance of reaching the semis.