British number one Johanna Konta beat Elise Mertens 6-3 7-5 in the first round of the Kremlin Cup in Moscow.
Konta sent a powerful forehand into the corner to break Mertens to love and take the opening set in 34 minutes.
Mertens, ranked 16 in the world, broke her rival for the only time in the first game of the second set but Konta recovered to level at 4-4.
The Belgian had to serve to stay in the match at 6-5 down but failed to do so as Konta broke to take victory.
The world number 44 will play Russia's Vitalia Diatchenko or Australian Daria Gavrilova in the second round.