World number 247 Maximo Gonzalez has knocked out an out-of-sorts Jerzy Janowicz in the first round of the US Open.
The Pole struggled with a back problem at Flushing Meadows as he succumbed to a 6-4 6-4 6-2 defeat.
The doctor first came on as Janowicz was already a set and an early break down in the second set. After a long consultation, he carried on but needed treatment at the changeover.
During the third set, the 14th seed had all but given up as Gonzalez stormed to an easy victory.
The 30-year-old Argentine will play either Jack Sock or Philipp Petzschner in the next round.
