Venus Williams displayed the mental strength that has made her a seven-time Grand Slam singles champion on Thursday, holding off a spirited challenge by Slovenian Dalila Jakupovic at the WTA Miami Open.
The 38-year-old American, a quarter-finalist at Indian Wells last week, turned back Jakupovic 7-5, 6-3 in 78 minutes to reach the second round after a rough start.
Jakupovic was serving for the first set and Williams was on the back foot before the qualifier wilted under the pressure and 43rd-ranked Williams booked a second-round matchup against Spanish 24th seed Carla Suarez Navarro.
Tenth seed Serena Williams, a 23-time Grand Slam singles champion and younger sister of Venus, will open in the second round against Sweden's Rebecca Peterson, who eliminated German qualifier Laura Siegemund 6-1, 5-7, 7-5.
Three consecutive breaks saw 80th-ranked Jakupovic ease into an early 3-2 lead with Williams struggling on serve, and she served for the first set at 5-4 before Williams answered to claim a set that saw seven service breaks in all.
Williams stormed ahead 5-1 in the second set and cruised from there.
Williams, in a record 20th Miami appearance, knows she faces a tougher test in Suarez Navarro even though she owns a 6-3 career edge on the Spaniard.
Mari Osaka, the older sister of world number one Naomi Osaka, was ousted in her opening match, falling to American Whitney Osuigwe 6-2, 6-4.
Canada's Bianca Andreescu, fresh off the Indian Wells title, rallied to beat Romania's Irina-Camelia Begu 4-6, 7-6 (7/2), 6-2 in her opening match.
World number two Petra Kvitova of the Czech Republic downed Greece's Maria Sakkari 6-1, 6-4, to become the first player into the third round.
In ATP first-round matches, Australia's Bernard Tomic dispatched Brazilian qualifier Thiago Monteiro 6-4, 6-1 and Aussie Jordan Thompson downed Britain's Cameron Norrie 4-6, 7-6 (7/5), 6-3.