And this time past year, Medvedev was also well down the ranks, at 84, after also playing on the Challenger tour, but he went on to win his first three career titles, and ended 2018 with a tour-leading 38 hard-court wins and a career-high ranking of 16.
Medvedev saved all eight of the break points he faced in an impressive 6-7 (2-7) 6-3 6-4 victory over Milos Raonic, who was beaten despite serving 29 aces.
It was in the ninth game of the third set when Medvedev earned his second service break - half of what he created - which proved to be decisive as the Russian player held his following serve to post his second win over Raonic in their second career match.
"He played incredible", Medvedev said of Nishikori.
"I'm happy to see him (Tsonga) back", Nishikori said.
Jo-Wilfried Tsonga has shown no signs of a seven-month tour absence through injury last season, reprising his form of more than a decade ago to beat Australian Alex de Minaur in the Brisbane International quarter-finals.
"I felt like I was too fast on the court today - I felt very good". He served out the set to level the match, 6-3.
"If I'm being really frank, I just feel like I had like the worst attitude today", the 21-year-old Osaka said.
"I always start with this tournament and Melbourne, [but I] couldn't make it past year".
"Last year I did a lot of that and I'm trying to change it more, and I think I have, towards the end of last year".
Tsurenko is 4-0 in finals, and is hoping to extend that streak when she takes on Karolina Pliskova, who defeated Donna Vekic 6-3, 6-4 to reach the title match.
The win is the second time that Pliskova has won the Brisbane International, thanking her Australian coach for rousing her when she was at her low point during the match.