Andrey Rublev returned to form by downing Stefanos Tsitsipas in their first match of the ATP Finals in Turin on Monday.
Rublev had only won two of his past seven contests before arriving at the season-ending tournament at the Pala Alpitour but saw off fourth seed Tsitsipas 6-4 6-4.
The fifth seed from Russia gained sweet revenge, having lost to his Greek opponent in this event in London last year.
Rublev did not face a break point as he levelled his head-to-head record with Tsitsipas at 4-4 with a statement win.
The Moscow native won 90 per cent of points behind his first serve and broke Tsitsipas once in each set, sealing victory in an hour and a half.
Rublev joined world number one Novak Djokovic at the top of the Green Group on a night to forget for Tsitsipas.
WINNERS/UNFORCED ERRORS
Rublev – 31/7
Tsitsipas – 31/17
ACES/DOUBLE FAULTS
Rublev – 9/3
Tsitsipas– 12/2
BREAK POINTS WON
Rublev – 2/7
Tsitsipas – 0/0