They swept the doubleheader, beating the Mets 8-4 in the opener and 9-8 in 10 innings during the nightcap when the temperature at first pitch was 36 degrees.
Serena had made hard work of beating another Russian, Vera Dushevina, in a three-set opener on Monday, but appeared in command against world number 18 Petrova as she won the first set.