Mardy Fish has been knocked out of the Australian Open after a straight-sets defeat to unseeded Colombian Alejandro Falla.

A disappointing performance from the eighth seed led to a 7-6 6-3 7-6 victory for Falla.

Falla matched Fish throughout the early exchanges and the 28-year-old was able to find the quality to defeat his American opponent in a first-set tie-break 7-4.

Fish failed to find his form in the second set and Falla took advantage of any available break points to wrap up the set 6-3.

A second tie-break followed for the pair and a much tighter affair ended with Falla emerging victorious.