China's Zhang Shuai and Mate Pavic of Croatia beat Japanese Ena Shibahara and Croatian Franko Skugor in the mixed doubles quarterfinals at the U.S. Open on Monday. 

Meanwhile, American Frances Tiafoe beat second seed Rafael Nadal of Spain 6-4, 4-6, 6-4, 6-3 in the men's singles fourth round. World No. 1 Iga Swiatek of Poland downed Jule Niemeier of Germany 2-6, 6-4, 6-0 to reach the women's singles last four.

Zhang and Pavic won the first set 7-6 (5), but lost the second 6-4. The pair then took the deciding third set 10-3.

The No. 2 seeds will next play against Belgian-French pair, Kirsten Flipkens and Edouard Roger-Vasselin, for a berth in the final. 

Earlier the same day, Zhang and Marta Kostyuk of Ukraine were edged out in the women's doubles third round, along with China's Xu Yifan and Yang Zhaoxuan.

(With input from Xinhua)