Washington, Aug 2 (IANS): No.7 seed American Madison Keys registered a win at the Citi Open for the first time in a decade, easing past Zheng Qinwen of China 7-5, 6-1 in the opener.

With a win on Tuesday night, Keys ended the five-match winning streak of 20-year-old Zheng, who won her first career WTA singles title on the clay courts of Palermo two weeks ago.

The American saved three break points at 4-4 in the first set to stay in front of Zheng, and Keys eventually converted her first set point at 6-5 by forcing an error with a penetrating backhand. Two of Zheng's 10 double faults ceded a 2-0 lead to Keys in the second set, and the seventh seed rolled to victory from there.

Keys will come back on Wednesday night for an all-American second-round tussle with Jennifer Brady, who picked up her first tour-level win in nearly two years on Tuesday.

Meanwhile, another American Frances Tiafoe opened his men's singles campaign with a tight 7-6(5), 7-6(5) win against Aslan Karatsev on Tuesday.

Playing in his first match since Wimbledon, the 25-year-old Tiafoe fought off a set point on serve at 5-4 in the second set to avoid going the distance and later in the tie-break, he won four consecutive points after falling behind 3/5.

After earning his second ATP Head-to-Head win against Karatsev, World No. 10 Tiafoe set a first-time meeting against 18-year-old Chinese star Shang Juncheng in the second round.