The Danish royals engaged in a friendly bit of competition as they competed in the annual Royal Run, founded by King Frederik in 2018.
The race took place in five different cities across Denmark on Monday, with King Frederik, Queen Mary and their four children participating in various distances.
Crown Prince Christian took on the 5km race in Viborg, with King Frederik later running the same distance in Horsens.
When asked whether he expected to beat his father on time, the 19-year-old told TV2 with a smile: "I highly expect that."
The teenager, who has just completed four months of military training with the Guard Hussar Regiment at the Antvorskov barracks in Slagelse, pipped his father to the post with a time of 21 minutes and 15 seconds. Frederik completed his 5km race in 25 minutes and 44 seconds.
As he kicked off the race day in Ribe on Monday morning, the Danish King, 57, said of his family's participation: "I am proud that the whole family is participating today. He [Crown Prince Christian] has completed his military service and is in the best shape he can be."
Christian is expected to begin his Lieutenant's training course in August.
Family outing
Crown Prince Christian's younger siblings, Princess Isabella, 18, and 14-year-old twins, Prince Vincent and Princess Josephine ran the One Mile family race together in Copenhagen/Frederiksberg.
Josephine then went on to compete in the 5km and 10km distances.
The teenager, who made her acting debut last year, was praised by her brothers for her challenge.
According to Billed-Bladet, her twin brother Vincent said: "I think it's really cool that she's taking on all three races, I'm proud."
Christian added: "I am very, very, very proud that Josephine is taking on all three. It has gone really well."
Meanwhile, Queen Mary, 53, participated in the 5km race in Korsør, with the royal handing out medals to other runners after she had crossed the finishing line.
Royal tour
King Frederik and Queen Mary will embark on their first official visit to the Faroe Islands on the Royal Ship Dannebrog from 11 to 13 June.
The royal couple will visit Tórshavn, Vágur, Fámjin, Tvøroyri and Eiði, where Frederik and Mary will have the opportunity to visit many aspects of Faroese society and greet Faroese people of all ages.