Challenger Ismaning 10/14 09:00 46 Tristan Lamasine v Sieber, Marc 6-3,6-2
Challenger Ismaning 10/13 10:25 45 Kern, Robin v Sieber, Marc 3-6,2-6
Challenger Ortisei 10/06 13:30 45 Sieber, Marc v Albano Olivetti 6-4,6-7,4-6
ITF Germany F14 10/04 15:05 26 Francesco Ferrari v Sieber, Marc 2-6,6-4,6-3
ITF Germany F14 10/02 10:00 25 Max Wiskandt v Sieber, Marc 2-6,0-6
ITF Germany F14 10/01 10:00 44 Sieber, Marc v von Der Schulenburg, Henry 6-1,6-2
ITF Germany F14 09/30 11:30 44 Sieber, Marc v Nystroem, Patrick 6-1,7-5
Challenger Sibiu Qual 09/16 12:00 46 Frunza, Nicolae v Sieber, Marc 6-4,6-3
Challenger Seville 09/01 16:00 45 [454] Sieber, Marc v Bernabe Zapata Miralles [276] 6-7,3-6
Challenger Mallorca 08/26 11:30 45 Federico Zeballos v Sieber, Marc 3-6,6-1,6-3
Challenger Meerbusch 08/14 12:30 25 [429] Sieber, Marc v Tatlot, Johan Sebastien [261] 6-7,6-4,4-6
Meerbusch, Allemagne, Qualifications 08/13 09:00 54 [348] Tristan Lamasine v Sieber, Marc [429] 6-7,5-7
Meerbusch, Allemagne, Qualifications 08/12 09:40 46 Sieber, Marc v Adrian Oetzbach 6-0,6-0
Meerbusch, Allemagne, Qualifications 08/11 11:45 45 Mats Rosenkranz v Sieber, Marc 3-6,3-6
Challenger Pullach Qual 08/04 09:00 45 [429] Sieber, Marc v Lenz, Julian [479] 4-6,6-4,4-6
Challenger Liberec Qual 07/29 08:30 46 Sieber, Marc v Marvin Moeller 2-6,5-7
Challenger Liberec Qual 07/28 08:00 45 [354] Juan Pablo Ficovich v Sieber, Marc [439] 3-6,6-3,3-6
Challenger Prague 07/24 11:30 25 [264] Nedovyesov, Aleksandr v Sieber, Marc [439] 6-0,6-4
Challenger Prague Qual 07/23 10:10 54 [407] Torebko, Peter v Sieber, Marc [439] 1-6,4-6
Challenger Prague Qual 07/22 14:10 46 [482] Dominik Kellovsky v Sieber, Marc [447] 3-6,6-7
Challenger Prague 07/21 14:05 45 Perchicot, Mathieu v Sieber, Marc 6-1,2-6,3-6
Germany F8, Singles 07/19 09:30 26 [447] Sieber, Marc v Heyman, Christopher [307] 1-6,5-7
Germany F8, Singles 07/17 14:05 25 [385] Viktor Durasovic v Sieber, Marc [447] 3-6,2-6
Challenger Caltanissetta 06/12 08:00 25 [146] Arevalo-Gonzalez, Marcelo v Sieber, Marc [412] 1-6,6-1,7-5
Challenger Caltanissetta Qual 06/11 10:15 54 [326] Souza, Joao Olavo v Sieber, Marc [412] 6-2,3-6,4-6
Challenger Caltanissetta Qual 06/10 11:30 46 [410] Sieber, Marc v Cias, Pawel [408] 6-0,6-1
Challenger Caltanissetta Qual 06/09 13:25 45 Balmashev, Mikhail v Sieber, Marc 0-6,1-6
Challenger Prostejov Qual 06/03 15:25 46 [410] Sieber, Marc v Satral, Jan [365] 6-4,3-6,4-6
Challenger Prostejov Qual 06/03 09:45 45 Nejedly, Pavel v Sieber, Marc 1-6,5-7
ITF Hungary F2 05/18 08:00 28 Mate Valkusz v Sieber, Marc 6-1,6-1