Novak Djokovic booked his place in the last four of the ATP Finals with a crushing 6-4 6-1 defeat of Russian Andrey Rublev at the Turin showpiece on Wednesday.
After the first nine games went with serve, Djokovic switched on the afterburners to outclass Rublev.
Rublev, who like Djokovic had won his opening match at the year-ender, capitulated when serving to stay in the opener, losing the set as Djokovic thumped a backhand return winner.
The second set was a non-event as five-time champion Djokovic roared to victory in little more than an hour.
Later in the Red Group, Russia's Daniil Medvedev takes on Greek Stefanos Tsitsipas.