Six-time champion Serena Williams progressed to the third round of the US Open with a 6-2 6-4 win over Russian Margarita Gasparyan in New York.
The American, 38, cruised through the opening set but found the world number 117 a tougher proposition in the second under the Arthur Ashe Stadium roof.
The pair broke each other twice before Williams secured a crucial third break in the 10th game to seal victory.
Williams now faces compatriot Sloane Stephens, the 2017 champion.
"She's such a good player - she plays so smooth," Williams said of Stephens. "She looks like she's not taking on energy, then 'blam' - there's five winners.