Receive Breaking News updates as they occur
Former champions Novak Djokovic and Andy Murray booked a tantalizing US Open quarter-final duel on Monday with straight-sets fourth-round victories. World number one and top seed Djokovic didn't let Philipp Kohlschreiber stand in the way of another Grand Slam last-eight appearance, defeating the 22nd seed from Germany 6-1, 7-5, 6-4 on another oppressively muggy New York day. Eighth-seeded Scot Murray advanced with a hard-fought 7-5, 7-5, 6-4 victory over ninth-seeded Jo-Wilfried Tsonga, avenging a loss to the Frenchman in the Toronto Masters last month. They are 2-2 in Grand Slam finals, including Murray's triumph over Djokovic in the 2012 final at Flushing Meadows for his first major crown.