Oh Phoebe knew the sweep kick was coming. When you spar with the Source of all Evil, not that she'd known Cole was that at the time, you have a wide repertoire of knowledge with both attack and defend moves. What Phoebe also knew was that Kate needed to beat the shit out of something, so she didn't counter like she normally would have with Cole. Instead, she let the sweep take her down but rolled quickly toward her feet once more.