Emil Ruusuvuori (; born 2 April 1999) is a Finnish professional tennis player. He reached a career high ATP singles ranking of World No. 40 on 21 November 2022. He is currently the No. 1 Finnish singles tennis player. He has a career-high doubles ranking of World No. 179 achieved on 2 May 2022. As a junior, Ruusuvuori was ranked as high as World No. 4 in the ITF combined junior rankings. In 2017, he reached the singles quarterfinals of the Australian Open boys' singles, the singles semifinals of the US Open boys' singles, and won the ITF Junior Masters. Ruusuvuori has also represented Finland in the Davis Cup, where he has a win–loss record of 5–5. In September 2019, he defeated reigning world number 5 and 2-time Roland Garros finalist Dominic Thiem in straight sets in a Davis Cup singles rubber. Junior career 2013–2016: Early junior career At the age of 14, nine years after he first began playing tennis, Ruusuvuori entered his first ITF Juniors tournament, the Nokia Junior Cup, in 2013. 2014 offered his first success, reaching two singles finals, two doubles finals, and winning two doubles titles. He saw additional success in 2015, including one final in both singles and doubles as well as another doubles title. Ruusuvuori made his singles breakthrough in 2016, winning four events in total. He continued his doubles success as well, winning three events and reaching the finals of two more. 2017: Junior Grand Slam debut and first ITF Futures title Ruusuvuori started his year in January at the AGL Loy Yang Traralgon Junior International, reaching the semifinals in both the doubles, with partner Michael Vrbenský of the Czech Republic, and singles. He then entered the Australian Open, his debut grand slam event, participating in both the boys' singles and doubles. In singles, he won his first three matches in straight sets before losing to Corentin Moutet in the quarterfinals. Partnering again with Vrbensky, he lost in the first round of the doubles. February saw Ruusuvuori compete in his first Davis Cup match, losing to Nikoloz Basilashvili of Georgia in straight sets. In March, he competed in the Croatia F3 Futures event in Umag, losing in the first round of singles qualifying. Ruusuvuori then returned to the junior tour, competing in the 33. Perin Memorial, where he reached the finals in singles, losing to Alen Avidzba of Russia in two sets.