The ATP Challenger Tour, known until the end of 2008 as the ATP Challenger Series, is a series of international men's professional tennis tournaments. The Challenger Tour events are the second-highest tier of tennis competition, behind the ATP Tour. The ITF World Tennis Tour tournaments are on the entry-level of international professional tennis competition. The ATP Challenger Tour is administered by the Association of Tennis Professionals. Players who succeed on the ATP Challenger Tour earn sufficient ranking points to become eligible for main draw or qualifying draw entry at ATP Tour tournaments. Players on the Challenger Tour are usually young players looking to advance their careers, those who fail to qualify for ATP events, or former ATP players looking to get back into the big tour.
Daniel Dutra da Silva is a professional tennis player from Brazil who competes mostly on the ATP Challenger Tour.
Alessandro Giannessi is a professional Italian tennis player. On 24 July 2017 he reached his highest ATP singles ranking of world No. 84 while his best doubles ranking was No. 171 on 14 October 2013.
Kaichi Uchida is a Japanese professional tennis player.
The Marbella Tennis Open is a professional tennis tournament played on clay courts. It is currently part of the Association of Tennis Professionals (ATP) Challenger Tour and WTA 125K series. The ATP event has been held annually in Marbella, Spain, from 2018 while the WTA edition started in 2022.
Nathaniel Lammons is an American professional tennis player who specializes in doubles. He has been ranked by the ATP as high as world No. 27 in doubles, which he achieved on 11 September 2023. He also attained a career-high singles ranking of world No. 591 in January 2019.
The Bratislava Open is a professional tennis tournament played on clay courts.
Juan Pablo Ficovich is an Argentine professional tennis player.
Zizou Bergs is a Belgian professional tennis player. He has a career high ATP singles ranking of World No. 112 achieved on 6 February 2023. He also has a career high ATP doubles ranking of World No. 289 achieved on 24 July 2023. He is currently the No. 3 Belgian singles tennis player.
Lukáš Klein is a Slovak professional tennis player. Klein has a career-high ATP singles ranking of World No. 133, achieved on 22 May 2023. He also has a career-high doubles ranking of World No. 240, achieved on 5 April 2021.
Camilo Ugo Carabelli is an Argentine professional tennis player.
Sergio Martos Gornés is a Spanish tennis player.
Riccardo Bonadio is an Italian tennis player.
Oleksii Krutykh is a Ukrainian tennis player.
Santiago Rodríguez Taverna is an Argentine professional tennis player.
The Sparta Prague Open Challenger is a professional tennis tournament played on clay courts. It is currently part of the Association of Tennis Professionals (ATP) Challenger Tour. It has been held in Prague, Czech Republic since 2000 on the TK Sparta Prague, founded in 1905 near Stromovka, inside Prague's Bubeneč district.
The 2022 Saturn Oil Open was a professional tennis tournament that was played on clay courts. It was the first edition of the tournament which was part of the 2022 ATP Challenger Tour. It took place in Troisdorf, Germany between 23 and 29 May 2022.
Aleksandar Kovacevic is an American professional tennis player.
Jelle Sels is a Dutch tennis player. Sels competes mainly in the Challenger tour circuit. He has a career high ATP singles ranking of world No. 127 achieved on 28 November 2022. He also has a career high doubles ranking of world No. 201 achieved on 20 June 2022.
The 2023 Saturn Oil Open was a professional tennis tournament that was played on clay courts. It was the second edition of the tournament which was part of the 2023 ATP Challenger Tour. It took place in Troisdorf, Germany between 29 May and 4 June 2023.
2022 Saturn Oil Open 
