The ATP Challenger Tour represents a litmus test, as those who succeed at this level often go on to become mainstays in the ATP top 50.
The Challenger Tour sits a tier below the ATP Tour, offering lower-ranked players an opportunity to boost their rankings and potentially qualify for ATP Tour events.
The Tour can also provide an opportunity for older players who are in the twilight of their careers, such as Stan Wawrinka.
One player currently competing on the Challenger Tour looks set to make big strides in the future, after winning multiple events during 2025.
Meet Nicolai Budkov Kjaer
Nicolai Budkov Kjaer could be the next bona fide star on the ATP Tour.
The 19-year-old Norwegian recently won his fourth Challenger Tour title of 2025 in Open de Vendee, France, defeating American Patrick Kypson 6-0, 6-3 in the final.
His success in Paris follows Challenger Tour title wins in Scotland, Finland and Kazakhstan.
Kjaer has a long history of success at the junior level. In 2024, he became the first Norwegian man to win a Grand Slam title at the professional or junior level after winning the Wimbledon Boys Singles title.
The 19-year-old, who trains in Oslo, Norway, also won the 2024 French Open boys’ doubles title while competing alongside Joel Schwärzler.
The former ITF junior world number one has competed for Norway at the Davis Cup on eight occasions. He has a record of 4-4.
Budkov Kjaer described Casper Ruud as a ‘big brother’
Casper Ruud, Norway’s highest-ranked male player in singles, has certainly set a great example for all young Norwegian stars aspiring to reach the top level.
The former world number two is a multiple Grand Slam finalist and the holder of 13 ATP Tour titles.
Speaking to the ATP Tour in March, Budkov Kjaer spoke of his relationship with Ruud, describing his compatriot as a ‘big brother.’
Budkov Kjaer said: “He’s like a big brother to me. He says some things here and there, and some tips and tricks.
“He’s really a great guy. What people say on the Tour, that he is one of the nicest, is really true in my opinion.
“He’s really a nice guy and I’m very happy to have a countryman representing us as a nation and hopefully I can represent our nation in the same way together with him in some years.
“It’s very cool to get messages from him every time, even though it’s usual. Every time I get a little more happy when I see a message from him.”
