The leading two positions have been occupied by a combination of the Big Four ever since Rafael Nadal climbed above Australia's Lleyton Hewitt to take second place on the ladder on 25 July, 2005.
Nadal, Federer, Novak Djokovic and Andy Murray have all had spells at No.1 in the years since then, and no other player has had a look-in on those leading two positions.
Within days, however, that is about to change, as the younger generation of players gains a first foothold in the top two.
The ATP, which runs the men's game, announced on Sunday (AEDT) that 25-year-old Medvedev is certain to nudge up one place from his current position of world No.3 when the rankings are published on 15 March.
The Russian is currently on 9735 points, 115 points behind Nadal, and he has a first-round bye at the Open 13 Marseille next week.
The ATP, tweeted: "With the release of next week's @atptour draws, @DaniilMedwed is confirmed to become World No. 2 in @FedEx ATP Rankings on 15 March. Medvedev will be the 1st player in the Top 2 since 25 July 2005 other than the Big 4 of @DjokerNole, @RafaelNadal, @rogerfederer and @andy_murray."
With the release of next week's @ATPTour draws, @DaniilMedwed is confirmed to become World No. 2 in @FedEx ATP Rankings on 15 March.— ATP Media Info (@ATPMediaInfo) March 6, 2021
Medvedev will be the 1st player in the Top 2 since 25 July 2005 other than the Big 4 of @DjokerNole, @RafaelNadal, @RogerFederer and @Andy_Murray.
Medvedev, who won the ATP World Tour Finals title in November and reached the Australian Open final last month, missed an early chance this week to move ahead of Nadal when he lost in the first round of the Rotterdam Open.