French teenager Luca Van Assche rallied for a 1-6, 7-6 (4), 6-4 victory over Switzerland's Stan Wawrinka in the first round Monday at the Srpska Open in Banja Luka, Bosnia and Herzegovina.

Van Assche, 18, will follow up his first career top 100 win with a second-round meeting against World No. 1 Novak Djokovic of Serbia, the top seed in the ATP 250 clay-court event.

Van Assche saved eight of 11 break points, including four at 5-5 of the second set. In the deciding set, he trailed 1-3 before winning four straight games.

Also Monday, Alexei Popyrin of Australia eliminated No. 5 seed Tallon Griekspoor of the Netherlands 7-6 (4), 7-6 (4) and Alex Molcan of Slovakia rallied to beat Japan's Taro Daniel 3-6, 7-5, 6-1.

BMW Open

Marcos Giron of the U.S. scored a 6-1, 5-7, 6-2 upset of seventh-seeded Spaniard Roberto Carballes Baena in first-round action in Munich, Germany.

Giron converted five of 14 break chances and 81 percent of the points (39 of 48) on his first serve in the two-hour and 12-minute victory in the ATP 250 clay-court tournament.

Flavio Cobolli of Italy also advanced with a 7-5, 6-1 defeat of Australia's Jordan Thompson and German wild card Yannick Hanfmann outlasted Brazil's Thiago Monteiro 6-7 (3), 7-6 (5), 6-2.

Barcelona Open Banc Sabadell

Ben Shelton took down fellow American Mackenzie McDonald 7-5, 6-4 to reach the second round in Spain.

Shelton struck nine aces and converted five of his six break chances in the 99-minute match. He next faces Norway star Casper Ruud, the No. 3 seed in the ATP 500 clay-court event. Shelton defeated Ruud in Cincinnati last year in straight sets.

Other first-round winners included Spain's Bernabe Zapata Miralles, Finland's Emil Ruusuvuori, Portugal's Nuno Borges, Argentina's Tomas Martin Etcheverry, Chile's Nicolas Jarry, Russia's Pavel Kotov and Slovakia's Jozef Kovalik.

World No. 2 Carlos Alcaraz of Spain is the top seed and opens against Borges.