AUCKLAND, New Zealand — Canada's Denis Shapovalov was defeated in his second-round match Wednesday at the ASB Classic in Auckland, New Zealand.

The unseeded resident of Richmond Hill, Ont., fell 6-2, 6-4 to No. 2 seed Juan Martin Del Potro of Argentina.

Shapovalov had defeated the 2009 U.S. Open champion in the second round of the Rogers Cup in Montreal last August.

The 18-year-old Canadian is now 0-2 to start the year after dropping his opening match of 2018 on Jan. 2 at the Brisbane International to Britain's Kyle Edmund in three sets.

Shapovalov began the ASB Classic ranked No. 50 in the world while Del Potro came in ranked No. 12.

Earlier, top-seed and defending champion Jack Sock of the U.S. made a surprise exit after losing 6-3, 6-3 to unseeded German Peter Gojowczyk.