faced Dominick Reyes on October 6, 2018, at UFC 229. He lost the fight via unanimous decision. 2019 Saint Preux was expected to face Misha Cirkunov on March 2, 2019, at UFC 235. However, on February 11, it was announced that Saint Preux suffered an injury and was pulled from the fight. He was replaced by Johnny Walker. Saint Preux faced Nikita Krylov in a rematch on April 13, 2019, at UFC 236. He lost the fight via a submission due to a rear-naked choke in round two. Saint Preux faced Michał Oleksiejczuk on September 28, 2019, at UFC on ESPN+ 18. He won the fight via submission due to a Von Flue choke in the second round; thereby extended his ending with this submission to a record four wins. The win also earned Saint Preux his sixth Performance of the Night bonus award. Saint Preux was briefly liked to face Ryan Spann on February 8, 2020, at UFC 247. However, promotion matchmakers elected to go in another direction and the pairing was scrapped from the event. Saint Preux was suspended for three months by USADA for tested positive for Ostarine and S-23, the family of selective androgen receptor modulators (SARMs), where the prohibited subsistence was found from a tainted supplement. The suspension retroactive from October 25, 2019, and he was eligible to fight again on January 25, 2020. 2020 Saint Preux was expected to face Shamil Gamzatov on April 25, 2020. However, Gamzatov was forced to pull from the event due to COVID-19 pandemic travel restriction, and Saint Preux was pulled from the event and was scheduled to meet Ion Cuțelaba at the event. However, on April 9, Dana White, the president of UFC announced that this event was postponed to a future date. On April 24, 2020, it was revealed that the fight against Cuțelaba was cancelled due to Cuțelaba not being allowed to leave his home country of Moldova due to a pandemic travel ban. Saint Preux moved up to the heavyweight division and faced Ben Rothwell at the UFC Fight Night: Smith vs. Teixeira on May 13, 2020. He lost the fight via split decision. Saint Preux was scheduled to face Shamil Gamzatov on April 25, 2020. However, Gamzatov was forced to pull from the event due to COVID-19 pandemic travel restriction The match was rescheduled on August 22, 2020, at UFC on ESPN 15. However,