UCC28180: How the IC corrects the power factor without Ac line Sense

Part Number:UCC28180

I am investigating the UCC28180. This IC has no Ac line Sense.

The IC can measure the line current and the PFC Output Voltage (Vsense). The measurement point of Vsense is just after the PFC diode where a smoothening capacitor is placed. This means that at this point the input Ac line phase information is lost. 

If the IC knows nothing abaout the input Ac line Voltage phase position, how will it be possible that the input current is synchronised with the input AC voltage? 

Any app-note describing how the average current mode control of PFC without Ac line sense works is appreciated.