Britain's Cameron Norrie has been beaten by teenage American qualifier Learner Tien in the opening round of the Mexican Open in Acapulco.

Norrie, who is now 74th in the world, was beaten 7-6 (7-5) 6-3 by the 19-year-old, who is ranked nine places below him.

The Briton had won the only previous meeting between the pair, in Hong Kong earlier this year.

Tien led 4-1 in the opener before Norrie recovered and served for the set at 5-4. But he was broken and Tien went on to take the subsequent tie-break and control the match after that.

Second seed Casper Ruud advanced to round two by beating France's Arthur Rinderknech 6-4 6-3 while American pair Tommy Paul and Ben Shelton, the third and fifth seeds respectively, also went through.