Li Na roars past Jankovic to US Open last eight

China's Li Na avenged her recent loss to Jelena Jankovic of Serbia by thrashing the former world No 1 in straight sets to reach the quarterfinals of the US Open.

The Chinese fifth-seeded showed no mercy against Jankovic, crushing the Serbian 6-3, 6-0 in 57 minutes to make her first Flushing Meadows last eight since 2009.

Li will face Russia's Ekaterina Makarova who later defeated Poland's third seed Agnieszka Radwanska in the quarters.