| Singles | |
|---|---|
| 2018 Koblenz Open | |
| Champion |  Mats Moraing |
| Runner-up |  Kenny de Schepper |
| Final score | 6–2, 6–1 |
Ruben Bemelmans was the defending champion but withdrew as he qualified for the 2018 Australian Open.
Mats Moraing won the title after defeating Kenny de Schepper 6–2, 6–1 in the final.
Andrey Kuznetsov (first round)
Marco Cecchinato (second round)
Sergiy Stakhovsky (semifinals) Oscar Otte (first round) Yannick Maden (quarterfinals) Kenny de Schepper (final)
Andrej Martin (first round)
Tommy Robredo (first round)| Semifinals | Final | ||||||||||||
| Alt |  Ilya Ivashka | 6 | 5 | 4 | |||||||||
| 6 | Kenny de Schepper | 3 | 7 | 6 | |||||||||
| 6 | Kenny de Schepper | 2 | 1 | ||||||||||
| WC | Mats Moraing | 6 | 6 | ||||||||||
| 3/Alt | Sergiy Stakhovsky | 4 | 3 | ||||||||||
| WC | Mats Moraing | 6 | 6 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | A Kuznetsov | 4 | 6 | 3 | |||||||||||||||||||||||
| Alt | I Ivashka | 6 | 4 | 6 | Alt | I Ivashka | 6 | 6 | |||||||||||||||||||
 K-M Maamoun | 3 | 3 | Q |  C Heyman | 4 | 4 | |||||||||||||||||||||
| Q | Christopher Heyman | 6 | 6 | Alt | I Ivashka | 6 | 6 | ||||||||||||||||||||
 E Leshem | 3 | 7 | 3 | 5 | Y Maden | 1 | 2 | ||||||||||||||||||||
 D Popko | 6 | 5 | 6 | D Popko | 5 | 4 | |||||||||||||||||||||
 A Pavlásek | 2 | 2 | 5 | Y Maden | 7 | 6 | |||||||||||||||||||||
| 5 | Y Maden | 6 | 6 | Alt | I Ivashka | 6 | 5 | 4 | |||||||||||||||||||
| 4 | O Otte | 66 | 3 | 6 | K de Schepper | 3 | 7 | 6 | |||||||||||||||||||
| A Vatutin | 78 | 6 | A Vatutin | 3 | 6 | 77 | |||||||||||||||||||||
 H Hurkacz | 6 | 6 | H Hurkacz | 6 | 0 | 65 | |||||||||||||||||||||
 A Balázs | 4 | 2 | A Vatutin | 6 | 67 | 1 | |||||||||||||||||||||
 E Gulbis | 4 | 6 | 1 | 6 | K de Schepper | 3 | 79 | 6 | |||||||||||||||||||
| WC | B Hassan | 6 | 3 | 6 | WC | B Hassan | 77 | 1 | 4 | ||||||||||||||||||
| T Gabashvili | 77 | 1 | 2 | 6 | K de Schepper | 64 | 6 | 6 | |||||||||||||||||||
| 6 | K de Schepper | 65 | 6 | 6 | |||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8/Alt | T Robredo | 1 | 7 | 66 | |||||||||||||||||||||||
| WC | J Choinski | 6 | 5 | 78 | WC | J Choinski | 3 | 6 | 4 | ||||||||||||||||||
| M Safwat | 3 | 7 | 6 | M Safwat | 6 | 3 | 6 | ||||||||||||||||||||
| Q | F Horanský | 6 | 5 | 3 | M Safwat | 2 | 1 | ||||||||||||||||||||
| N Kuhn | 6 | 6 | 3/Alt | S Stakhovsky | 6 | 6 | |||||||||||||||||||||
| Q |  M Ymer | 3 | 3 | N Kuhn | 4 | 3 | |||||||||||||||||||||
| Q | J De Loore | 2 | 3 | 3/Alt | S Stakhovsky | 6 | 6 | ||||||||||||||||||||
| 3/Alt | S Stakhovsky | 6 | 6 | 3/Alt | S Stakhovsky | 4 | 3 | ||||||||||||||||||||
| 7 | A Martin | 2 | 4 | WC | M Moraing | 6 | 6 | ||||||||||||||||||||
| Z Kolář | 6 | 6 | Z Kolář | 2 | 1 | ||||||||||||||||||||||
 Y Uchiyama | 6 | 6 | Y Uchiyama | 6 | 6 | ||||||||||||||||||||||
| WC | M Möller | 3 | 1 | Y Uchiyama | 4 | 62 | |||||||||||||||||||||
 T Brkić | 77 | 5 | 2 | WC | M Moraing | 6 | 77 | ||||||||||||||||||||
| WC | M Moraing | 62 | 7 | 6 | WC | M Moraing | 6 | 6 | |||||||||||||||||||
| A Arnaboldi | 77 | 4 | 2 | 2 | M Cecchinato | 4 | 4 | ||||||||||||||||||||
| 2 | M Cecchinato | 62 | 6 | 6 | |||||||||||||||||||||||
Stéphane Bohli was the defending champion, but decided not to participate.
Tomáš Berdych was the defending champion but withdrew because of a wrist injury.
Richard Gasquet won the title, defeating Benoît Paire in an all-French final, 6–2, 6–3.
Grégoire Burquier was the defending champion but decided not to participate.
Jesse Huta Galung won the final 7–6(7–4), 4–6, 7–6(7–3) against Kenny de Schepper.
Two-time defending champion Rafael Nadal successfully defended his title, defeating Nicolás Almagro in the final, 6–4, 6–3. It was his record-extending eighth Barcelona Open title.
Andy Roddick was the defending champion, but he retired from professional tennis in September 2012. Feliciano López won the title beating in the final Gilles Simon, 7–6(7–2), 6–7(5–7), 6–0 for the third title of his career, first since 2010.
Gilles Simon was the defending champion, but withdrew with a right wrist injury before the tournament began.
John Isner was the defending champion, but withdrew to concentrate on preparing for the Australian Open.
Jiří Veselý won the title, defeating Adrian Mannarino in the final, 6–3, 6–2.
Defending champion Kei Nishikori successfully defended his title, defeating Pablo Andújar in the final, 6–4, 6–4, to win the singles title at the 2015 Barcelona Open.
Richard Gasquet won the title, defeating Nick Kyrgios in the final, 6–3, 6–2.
David Goffin was the defending champion, but withdrew before the tournament began.
David Goffin was the defending champion but chose not to participate this year.
Andy Murray was the defending champion, but chose not to participate.
David Ferrer won the title, defeating Steve Johnson in the final, 4–6, 6–4, 7–5.
Richard Gasquet was the defending champion and successfully defended his title, defeating Paul-Henri Mathieu in the final, 7–5, 6–4.
Gilles Simon was the defending champion, but lost in the first round to Teymuraz Gabashvili.
Philipp Kohlschreiber was the defending champion, but lost in the second round to Karen Khachanov.
Richard Gasquet was the two-time defending champion, but lost to Alexander Zverev in the final, 6–7(4–7), 3–6.
Fabio Fognini was the defending champion, but lost in the quarterfinals to Andrey Rublev.
Lucas Pouille was the defending champion, but lost in the second round to Marius Copil.
Alexander Zverev was the defending champion, but chose not to participate this year.
Peter Gojowczyk was the defending champion, but lost to Kei Nishikori in the second round.