| Singles | |
|---|---|
| 2017 Guzzini Challenger | |
| Champion |  Viktor Galović |
| Runner-up |  Mirza Bašić |
| Score | 7–6(7–3), 6–4 |
Illya Marchenko was the defending champion but chose not to defend his title.
Viktor Galović won the title after defeating Mirza Bašić 7–6(7–3), 6–4 in the final.
Luca Vanni (semifinals)
Quentin Halys (quarterfinals)
Adrián Menéndez Maceiras (quarterfinals) Kenny de Schepper (second round) Mirza Bašić (final)
Egor Gerasimov (second round) Salvatore Caruso (semifinals) Aldin Šetkić (first round)| Semifinals | Final | ||||||||||||
| 1 | Luca Vanni | 77 | 64 | 62 | |||||||||
| 5 | Mirza Bašić | 63 | 77 | 77 | |||||||||
| 5 | Mirza Bašić | 63 | 4 | ||||||||||
| Q | Viktor Galović | 77 | 6 | ||||||||||
| 7 | Salvatore Caruso | 3 | 3 | ||||||||||
| Q | Viktor Galović | 6 | 6 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | L Vanni | 3 | 6 | 6 | |||||||||||||||||||||||
 M Safwat | 6 | 3 | 4 | 1 | L Vanni | 6 | 2 | 6 | |||||||||||||||||||
| Q |  F Nielsen | 4 | 77 | 6 | Q | F Nielsen | 2 | 6 | 2 | ||||||||||||||||||
 A Velotti | 6 | 63 | 3 | 1 | L Vanni | 77 | 6 | ||||||||||||||||||||
 D Petrović | 1 | 62 |  M Moraing | 63 | 3 | ||||||||||||||||||||||
| M Moraing | 6 | 77 | M Moraing | 3 | 77 | 79 | |||||||||||||||||||||
| WC | G Mager | 63 | 4 | 6 | E Gerasimov | 6 | 63 | 67 | |||||||||||||||||||
| 6 | E Gerasimov | 77 | 6 | 1 | L Vanni | 77 | 64 | 62 | |||||||||||||||||||
| 3 | A Menéndez Maceiras | 6 | 77 | 5 | M Bašić | 63 | 77 | 77 | |||||||||||||||||||
| Q |  E Karlovskiy | 2 | 64 | 3 | A Menéndez Maceiras | 5 | 7 | 6 | |||||||||||||||||||
| A Bega | 7 | 6 | A Bega | 7 | 5 | 4 | |||||||||||||||||||||
 E Leshem | 5 | 2 | 3 | A Menéndez Maceiras | 6 | 3 | 3 | ||||||||||||||||||||
| M Hamou | 6 | 63 | 78 | 5 | M Bašić | 3 | 6 | 6 | |||||||||||||||||||
| P Krstin | 2 | 77 | 66 | M Hamou | 4 | 2 | |||||||||||||||||||||
| WC | J Ocleppo | 6 | 3 | 1 | 5 | M Bašić | 6 | 6 | |||||||||||||||||||
| 5 | M Bašić | 3 | 6 | 6 | |||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 7 | S Caruso | 77 | 6 | ||||||||||||||||||||||||
 Petr Michnev | 65 | 2 | 7 | S Caruso | 65 | 6 | 7 | ||||||||||||||||||||
| A Kudryavtsev | 6 | 2 | 3 |  R Ramanathan | 77 | 3 | 5 | ||||||||||||||||||||
| R Ramanathan | 4 | 6 | 6 | 7 | S Caruso | 6 | 6 | ||||||||||||||||||||
| A Arnaboldi | 77 | 6 | A Arnaboldi | 3 | 1 | ||||||||||||||||||||||
 M İlhan | 64 | 2 | A Arnaboldi | 77 | 6 | ||||||||||||||||||||||
| J Eysseric | 3 | 6 | 1 | 4 | K de Schepper | 65 | 4 | ||||||||||||||||||||
| 4 | K de Schepper | 6 | 3 | 6 | 7 | S Caruso | 3 | 3 | |||||||||||||||||||
| 8 | A Šetkić | 3 | 61 | Q | V Galović | 6 | 6 | ||||||||||||||||||||
| WC | A Vavassori | 6 | 77 | WC | A Vavassori | 1 | 3 | ||||||||||||||||||||
| WC | Edoardo Eremin | 79 | 3 | 2 | Q | V Galović | 6 | 6 | |||||||||||||||||||
| Q | V Galović | 67 | 6 | 6 | Q | V Galović | 65 | 7 | 6 | ||||||||||||||||||
 Y Mertens | 3 | 6 | 77 | 2 | Q Halys | 77 | 5 | 4 | |||||||||||||||||||
 D Popko | 6 | 3 | 60 | Y Mertens | 1 | 4 | |||||||||||||||||||||
| Q | A Çelikbilek | 1 | 62 | 2 | Q Halys | 6 | 6 | ||||||||||||||||||||
| 2 | Q Halys | 6 | 77 | ||||||||||||||||||||||||
Tommy Haas was the defending champion but was knocked out by top seed Roger Federer in the semifinals. Federer won 6–7(5–7), 6–3, 6–4 against Mikhail Youzhny to claim a record sixth title and his first since 2008.
Juan Martín del Potro was the defending champion but decided not to compete.
Tommy Haas won the title, defeating Robin Haase in the final, 6–3, 4–6, 6–4.
Gilles Müller was the defending champion, but he did not participate in 2015.
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.
This was the first edition of the tournament.
Guillermo García López was the defending champion, but lost in the semifinals to Fernando Verdasco.
Andy Murray was the defending champion, but chose not to participate this year.
Rafael Nadal was the defending champion, but chose not to participate this year.
Evgeny Donskoy was the defending champion but chose not to defend his title.
Chan Hao-ching and Chan Yung-jan were the defending champions, but lost in the semifinals to Sania Mirza and Barbora Strýcová.
Denis Istomin was the defending champion but lost in the final to Konstantin Kravchuk.
Malek Jaziri was the defending champion but chose not to defend his title.
Diego Schwartzman was the defending champion, but lost in the semifinals to Marin Čilić.
Luca Vanni was the defending champion but chose not to defend his title.
Grigor Dimitrov was the defending champion, but withdrew before the tournament because of a shoulder injury.
Two-time defending champion Rafael Nadal defeated Kei Nishikori in the final, 6–3, 6–2 to win the singles tennis title at the 2018 Monte-Carlo Masters. It was his record-extending 11th Monte-Carlo Masters title and his record 31st Masters title. By winning the title, Nadal also retained the ATP no. 1 singles ranking. He did not lose a single set during the tournament.
Rafael Nadal defeated Stefanos Tsitsipas in the final, 6–2, 7–6(7–4) to win the men's singles tennis title at the 2018 Rogers Cup. It was his fourth Canadian Open title.
Mirza Bašić was the defending champion but lost in the first round to Martin Kližan.
Ričardas Berankis was the defending champion but lost in the semifinals to Kamil Majchrzak.
Daniel Brands was the defending champion but chose not to defend his title.