Williams, 46, was beaten 6-2, 6-2 by the 25-year-old qualifier in just one hour and five minutes on the grandstand court at the Lindner Tennis Center. The result extended Williams’ singles losing streak to 13 matches.
The American received a wild-card entry into the WTA 1000 tournament but was unable to end a drought that has kept her without a singles victory since July 2025.
Arango, ranked 95th in the world, made an impressive start by breaking Williams’ serve in the opening game. She maintained the advantage throughout the match, converting four of her five break-point opportunities and winning 71 percent of points behind her first serve.
Williams, meanwhile, struggled to make the most of her opportunities. She had just one break-point chance and failed to convert it, while winning only 41 percent of her first-serve points.
Arango said taking an early lead helped settle her nerves and allowed her to dictate the contest.
“That kind of eased my nerves a little bit of having maybe a little bit of breathing room. And then I think I just did a good job of staying on it, trying to make her play as much as possible,” Arango said.
The Colombian will now face defending champion and No. 7 seed Iga Swiatek in the second round.
Williams’ last singles win came at the Washington tournament in 2025, when she defeated Peyton Stearns. Despite Friday’s defeat, she felt there were positive signs in her performance, particularly in her ability to control points.
“I think that at all times I was really controlling the point, but unfortunately didn’t finish it the way I wanted to,” Williams said. “The encouraging part is that I’m controlling the shots, but I have to just get a little more consistent on that last part.”
The Cincinnati appearance marks Williams’ 11th at the tournament. Although her singles campaign is over, she will remain in Ohio to compete in the doubles event alongside her younger sister, Serena Williams.
The sisters received a wild-card entry and will play Marta Kostyuk and Peyton Stearns in the first round. Their doubles campaign is scheduled to begin on Sunday.
Venus and Serena Williams last teamed up in doubles at the 2022 US Open. They had been scheduled to reunite at Wimbledon before Serena withdrew because of an injury.
Looking ahead to their return as a doubles team, Venus said she was eager to compete alongside her sister again.
“I’m excited and hope that we can both go into it fresh, on our toes and ready. I’ll be preparing for that,” she said.
Venus Williams is also scheduled to compete in mixed doubles at the US Open later this month, where she is set to partner Kazakhstan’s Alexander Bublik.