The 24-year-old American is yet to drop a set at the Brisbane International this week, adding the in-form compatriot Kovacevic to his list of scalps after a 7-6 (7-4) 6-4 Saturday win.Â
The world No.33 will play current world No.13 Medvedev, who estimates he's playing at a "top-five" level after booking his second Brisbane final in as many visits.
Medvedev was pushed by another emerging US star, 21-year-old Alex Michelsen in a 6-4 6-2 win that stretched one hour and 42 minutes and featured a string of long deuce games.
The stylish, versatile Michelsen lived and died at the net, with a handful of loose volleys the difference in a tight first set he was initially in control of.
The Russian, a three-time Australian Open finalist, was beaten in the final in his only other visit to Brisbane in 2018 and has rediscovered some of his best tennis after two barren seasons by his standards.
"It was not easy at all; the score doesn't reflect completely the match," Medvedev, chasing a 22nd Tour title, said.
"But I'm happy, that in the most important moments today, I managed to be better than Alex.
"That's what you have to do to win the match."
Sunday will be Nakashima's fourth final, but first since claiming his maiden title, in his native San Diego, in 2022.
The three Americans who occupied the Brisbane final four are among 15 in the world's top 89, with Nakashima sixth in that list.
"Super tough match, right from the beginning," he said.
"We're (Kovacevic) really good friends, have been practising a lot the last month or so and it's great to see him playing well at these kind of tournaments.
"My team and I put a lot of hard work in the last month or so, making sure the game is nice and tight, and we're happy it's paying off the first week of the year and we'll continue to improve."
