Borna Coric became the first casualty on the opening day of Aircel Chennai Open, bowing out to qualifier Hyeon Chung 3-6, 5-7 on Monday.

For over two hours, the two played long, draining rallies, more often in Borna’s service games with Chung managing effective returns to induce errors from the Croat.

If Coric played a brilliant point, he invariably lost the next, his seemingly long hours of practice over the last few days in the courts of Nungambakkam doing little against an opponent, who made his way into the main draw after two wins in the qualifiers.

From the start, Chung made it clear that he was no pushover. Though the two traded breaks right at the start, the Korean always looked more assured. At 3-5, Coric, facing his second break point, dished out a weak serve and followed it with defensive push to Chung's side. The Korean had enough time to place a forehand winner at the corner baseline to take the first set.

The second set had longer rallies, with many games extending over eight minutes and Coric playing a bit more confidently. At 4-4, Coric broke Chung. But as was the case in the first set, Coric found the net way too often to lose his service game easily. He conceded the set 5-7 and with it, the match.

"I wasn't serving well due to which I missed a couple of important points," Coric said after the game.

The 20-year-old Chung will face Israel’s Dudi Sela in the second round. Sela upset higher ranked Bosnia & Herzegovina player Damir Dzumhur 6-2, 6-2.

Earlier, Daniil Medvedev overcame Brazilian Thiago Montiero's challenge, winning 6-3, 6-3 an insipid encounter that lasted for an hour and 36 minutes.

Medvedev was running away with the game with a 4-1 lead against an erring Brazilian who found his forehands sailing long or catching the net. With the wind strong, both had a tough time getting their slices past the net. Though Medvedev looked more flustered, bouncing his racquet at least thrice, he won the crucial moments well with some good serves.

Steve Darcis beat qualifier Nikola Mektic 6-2, 6-3 while Jozef Kovalik defeated Gastao Elias 6-7 (5), 6-4, 6-2 to advance to the second round.

In the doubles, India’s Vishnu Vardhan and N. Sriram Balaji bowed out with a straight-set loss to Swedish duo Johan Brunstrom and Andreas Siljestrom.

The results (first round, Indians unless specified):

Singles: Daniil Medvedev (Rus) bt Thiago Monteiro (Bra) 6-3, 6-3; Hyeon Chung (Kor) bt Borna Coric (Cro) 6-3, 7-5; Dudi Sela (ISR) bt Damir Dzumhur (Bih) 6-2, 6-2; Jozef Kovalik (Svk) bt Gastao Elias (Por) 6-7 (5), 6-4, 6-2; Steve Darcis (Bel) bt Nikola Mektic (Cro) 6-2, 6-3; Jurgen Melzer (Aut) & Renzo Olivo (Arg) bt Andre Begemann (Ger) & Yen-Hsun Lu (Tpe) 4-6, 7-6 (3) 11-9.

Doubles: Jurgen Melzer (Aut)/Renzo Olivo (Arg) bt Andre Begemann (Ger)/Yen-Hsun Lu (Tpe) 4-6, 7-6 (3) 11-9. Johan Brunstrom (Swe)/ Adreas Siljestrom (Swe) bt N. Sriram Balaji/Vishnu Vardhan 6-2, 6-4.