Emma Hinze and Lea Sophie Friedrich are the German duo duelling for overall victory in the women's sprint league in the UCI Track Champions League.
They head into the double-header in London with Hinze in first and Friedrich in second, but despite their fierce rivalry on the track, they are the best of friends off it and became - alongside Pauline Grabosch - team sprint world champions in October.
And two-time Olympic gold medallist Kristina Vogel - a lead analyst at the UCI Track Champions League - says the Hinze-Friedrich rivalry reminds her of her duels with Miriam Welte.
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"Lea and Emma remind me of Miriam and me," Vogel told Eurosport Germany.
"What set us apart from all the sprint teams in the world at the time was that we got along really well and were best friends. And you can tell that Emma and Lea also love each other."
Vogel and Welte dominated the sprint scene roughly 10 years ago and in 2012 they became team sprint Olympic champions in the same London velodrome where the action kicks back into gear this weekend. But they also competed against each other in the sprint and keirin.
"No inch is given to each other on the track," she said.
You want to defeat each other. But the two can easily separate that and after the duels work together again towards the goal of the Olympic team sprint victory.

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Nevertheless, Vogel also knows that a friendship can make racing against each other even more difficult, especially when training together and competing for their country.
"There is always a certain pecking order in the team - and that can rattle the comradery. You also know each other very well and want to use that, but at the same time not play unfairly against your friend. I always found it more difficult against Miriam than against others."
After two rounds of racing, Hinze has 37 points and holds an 11-point gap over Friedrich ahead of the double-header in London starting on December 3.
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The UCI Track Champions League returns for round three on December 3 and you can watch all of the action live on the Eurosport app, eurosport.co.uk and discovery+. Find out more about the "mind-blowing" new era for track cycling.
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