Nicolás Almagro was the two-time defending champion but decided not to participate.
Albert Montañés won the title, defeating Gaël Monfils in the final, 6–0, 7–6.(7–3)
On the first round match between Germans Julian Reister and Tim Puetz, Reister won the match with a golden set on the third and deciding set.
Rafael Nadal was the defending champion but chose not to compete.
David Goffin was the defending champion, but withdrew before the tournament began.
Marco Cecchinato was the defending champion but chose not to participate.
Jack Sock was the defending champion, but lost in the second round to Peter Gojowczyk.
Alexandr Dolgopolov was the defending champion, but withdrew before the tournament began.
Rogério Dutra Silva was the defending champion but lost in the quarterfinals to Carlos Gómez-Herrera.
The 2018 French Open – Men's Singles Qualifying was a series of tennis matches which took place 21 May 2018 to 25 May 2018 to determine the sixteen qualifiers into the main draw of the 2018 French Open – Men's singles. Eight competitors also qualified as lucky losers.
Two-time defending champion Rafael Nadal defeated Stefanos Tsitsipas in the final, 6–2, 6–1 to win the singles tennis title at the 2018 Barcelona Open. Nadal did not drop a set en route to his record-extending eleventh Barcelona Open title and his 20th ATP 500 title overall, equaling Roger Federer's record. He retained the world No. 1 singles ranking with the win. It was Tsitsipas' first ATP Tour final.
The 2018 Croatia Open Umag was a men's tennis tournament played on outdoor clay courts. It was the 29th edition of the Croatia Open, and part of the ATP World Tour 250 Series of the 2018 ATP World Tour. It took place at the International Tennis Center in Umag, Croatia, from 15 July through 22 July 2018.
Laslo Đere won the title – the first of his career – defeating Félix Auger-Aliassime in the final, 6–3, 7–5. No seeded players reached the quarterfinals, and only one seed won his first-round match.
Marco Cecchinato was the defending champion but chose not to defend his title.
Dominic Thiem defeated Roger Federer in the final, 3–6, 6–3, 7–5 to win the men's singles tennis title at the 2019 Indian Wells Masters. It was his maiden ATP Tour Masters 1000 title, and he became the first Austrian to win a Masters title since Thomas Muster won the 1997 Miami Open.
Novak Djokovic defeated Stefanos Tsitsipas in the final, 6–3, 6–4 to win the men's singles tennis title at the 2019 Madrid Open. With the win, Djokovic tied Rafael Nadal's record of 33 Masters 1000 singles titles. He did not lose a single set in the entire tournament.
Defending champion Rafael Nadal defeated Novak Djokovic in the final, 6–0, 4–6, 6–1 to win the men's singles tennis title at the 2019 Italian Open. It was his record-extending ninth Italian Open title and record 34th ATP Masters 1000 title.
Marco Cecchinato was the defending champion, but lost in the first round to Aljaž Bedene.
Daniil Medvedev defeated Alexander Zverev in the final, 5–7, 6–4, 6–1 to win the singles tennis title at the 2020 Paris Masters.
Stefanos Tsitsipas defeated Andrey Rublev in the final, 6–3, 6–3 to win the singles tennis title at the 2021 Monte-Carlo Masters. It was his first ATP Tour Masters 1000 title, making him the first Greek to win a Masters tournament. Rublev was also in contention for his maiden Masters 1000 title.
Alexander Zverev defeated Matteo Berrettini in the final, 6–7(8–10), 6–4, 6–3 to win the men's singles tennis title at the 2021 Madrid Open. It was Zverev's fourth Masters 1000 title, his first since Madrid 2018, and his 15th career ATP Tour singles title overall. Berrettini was in contention to become the second Italian to be a Masters 1000 champion.
Marco Cecchinato 
Guido Pella 
