WATCH: Roger Federer warms up with young cancer survivor at U.S. Open

Awesome moment between Roger Federer and a young cancer survivor.

Before Roger Federer took the court against Philipp Kohlschreiber at the U.S. Open Monday night, he warmed up on the practice court with a young cancer survivor. 

Mark Krajekian considers Federer his hero, according to ESPN. With hundreds of people watching, Krajekian and Federer rallied on the practice court prior to Monday's fourth-round match. 

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Little boy Marc Krajekian who fought cancer got to play with his idole #Federer #usopen17 #RTSsport pic.twitter.com/VM1yccybn0

— Musy Isabelle (@Isabellemusy) September 4, 2017

Here's an angle from the stands: 

Roger had a little hitting partner for a bit during today's practice-cancer survivor Marc Krajekian😘❤️#Federer #usopen (🎥via @dawnlight627 ) pic.twitter.com/CAS2zWR4jI

— Scarlett (@Scarlett_Li) September 4, 2017

If Kohlschreiber goes for the lob on Monday, we can assume Mark Krajekian gave him the inspiration.