The American started with Witt about a week and a half ago.
The Poles pushed past a pair of Czechs on Thursday in Prague.
"I'm happy I get to do this one more time," Andy Murray said of his Olympic farewell.
World No. 4 pulls out of Paris.
"Expectations are always high," top-seeded Novak Djokovic said of his Paris Olympic goal.
The three-time Grand Slam champion will finish her career playing for her country.
The Dane announced the news on Tuesday.
