The second-seeded Greek had taped his shoulder and appeared to be struggling with his backhand, which Australian opponent Jordan Thompson (ranked 87) took advantage of in a match that ended 7-6 (7-0), 4-6, 7 -6 (7-5).
- I got a tough draw but I got through it.
These are the matches I want to play, 87th-ranked Thompson told Reuters.
Next, Thompson will face Chilean qualifier Alejandro Tabilo, ranked 187th in the world.
Also from the second round are Norway's Casper Ruud, who knocked out Argentina's Diego Schwartzman in straight sets, and Finland's Emil Ruusuvuori, who defeated Roberto Bautista Agut, Spain.
In the next round, Ruud faces the 97th ranked Chilean Cristian Garin and Ruusuvuori will face the 14th ranked German Alexander Zverev.