Monaco won the tournament in 2012. It was Melzer's 2016 Tour debut after winning three Challenger Series titles.
American Denis Kudla also advanced, fighting off Germany's Mischa Zverev 6-3, 6-7 (2), 7-6 (2). South Korean teenager Hyeon Chung squandered a second-set match point, then made short work of Victor Estrella Burgos of the Dominican Republic 6-4, 6-7 (5), 6-0.
Chung, 19, played in just his fifth ATP World Tour main-draw match. Currently ranked 71st, he was named the ATP's Most Improved Player of the Year for 2015.