Started playing tennis in Oslo, Norway when he was six. Went to a tennis class close to his school to try the sport, and liked it.
Is coached by his father, Alexander Kjaer.
Describes his playing style as 'aggressive, quite bold and sometimes weird'.
Favourite shot is serve. Favourite surface is grass.
Favourite cities on Tour so far are Stockholm, because it reminds him of Norway, and Bastad.
Tennis idol is his father. 'It doesn’t really matter what results I do, as long as he is proud and happy, I am happy.'
Off court, describes himself as 'relaxed, kind of goofy and sometimes funny'
Loves ice hockey. Favourite team is Vålerenga in Norway.
Favourite hobbies are playing ice hockey in the off season, spending time with friends and family, and playing golf.
Favourite movie is Cars, and his favourite TV series is The Last Dance: 'Michael Jordan was such a [dedicated] athlete. The prime example of how competitive an athlete can be.'
Favourite musicians are Drake and The Weeknd, as well as Norwegian groups Bausa and Streetboys.
Favourite book is the autobiography of Norwegian cross-country skier Petter Northug.
Favourite food is a burger.
Favourite subject at school was maths.
Ideal day without tennis is waking up late, going to a coffee shop for a bun and coffee. Then spend time with friends and have dinner with family.