Andy Murray (GBR)  vs Kei Nishikori (JPN) . These two have played ten times on tour before, and the 3-time major champion leads their rivalry 8-2 however the last time they played was in the 2016 U.S. Open quarterfinals and Nishikori won a come-from-behind victory 7-5 in the fifth set. In 2017 both Murray and Nishikori have not been playing well, with the current World #1 amassing a 16-7 record (1 title, in Dubai) while Nishikori is 20-8 (no titles). Murray reached the final here last year and he has exceeded expectations to reach the quarterfinal but he actually has a pretty good chance to reach the final again this year. Mad Professah's pick: Murray.
Stan Wawrinka (SUI)  vs Marin Cilic (CRO) . Both Cilic and Wawrinka have been blasting their way through the draw for four rounds without dropping a set, so clearly for at least one of them this streak is going to have to end. Surprisingly, these two have played 13 times and Wawrinka has won all but two of these matches. Clay is one of Wawrinka's stronger surfaces, and two years ago he won this title by shocking Djokovic in the final after the Serb easily defeated Nadal in the quarterfinal. He's looking in a similar form and will almost certainly be looking forward to a rematch of last year's semifinal he lost to Murray last year to see if he can flip the script. Mad Professah's pick: Wawrinka.
Rafael Nadal (ESP)  vs Pablo Carreno Busta (ESP)
Novak Djokovic (SRB)  vs Dominic Thiem (AUT) . This match-up should be the most intriguing and exciting of the four quarterfinals. Thiem is the only player to have defeated Nadal on clay this year and last year had his breakthrough into his first major semifinal here at Roland Garros and is now firmly ensconced in the Top 10. It must be noted that Thiem is another one of the four quarterfinalists who has not dropped a set at this year's French Open but also note that last year he was completely outclassed by Djokovic in that major semifinal. However neither Thiem nor Djokovic are the same player they were last year, with Thiem is playing much better than last year while Djokovic is playing much worse. Although Thiem has won two consecutive sets in one match against Nadal, Djokovic has won three consecutive sets at Roland Garros, and he is the only active player on tour to do that. However, ever since winning the Nole Slam here last year Djokovic has not been the same player and it is not clear which player has the best chance at stopping Nadal from winning his 15th major. My guess is that it will be whomever wins this match. Mad Professah's pick: Thiem.