AUCKLAND: US top seed Ben Shelton’s preparation for the Australian Open was dealt a blow Wednesday with an upset loss to Czech teen sensation Jakub Mensik at the Auckland Classic.

Playing his first match in nearly two months, world number 21 Shelton was beaten 7-6 (7/2), 4-6, 7-5 in the second round by the powerful Mensik. A clash of two of the world’s premier young players ended after more than two and a half hours when Shelton’s serve was broken for the first time, in the 12th game of the third set.

The 22-year-old American, who received a bye through the first round, served strongly but couldn’t match the consistency of his 19-year-old opponent’s groundstrokes. Left-hander Shelton will have little match play under his belt heading to the Grand Slam tournament in Melbourne, having not previously played since representing the US in the Davis Cup nearly two months ago.