Looks like Jack Sock needed a little extra help in the secondary when trying to cover Ryan Harrison.

The two Americans, who are in London for the Nitto ATP Finals (Sock is in singles and Harrison is in doubles with Michael Venus), broke up the practice routine with a little toss-and-catch. Harrison’s smooth route-running left Sock grasping at air.

Both players are among the biggest fans of the NFL in tennis.

For Harrison, he bleeds black and gold as a die-hard fan of his hometown team, the New Orleans Saints. Sock is a card-carrying member of the Chiefs Kingdom, supporting Kansas City.

Harrison’s Saints won on Sunday to take their record to 7-2 to stay atop their division. Sitting on top in their division, too, is Sock’s Chiefs with a 6-3 record. With both teams playing in opposite conferences and no regular-season matchups this year, the only time they could meet this year is in the Super Bowl.

While their teams continue their push, Sock and Harrison get ready to make moves of their own in London. Sock, 0-1 in round-robin play after losing to Roger Federer, takes on Marin Cilic next. Harrison and Venus, who beat Henri Kontinen and John Peers in their first match, face Pierre-Hugues Herbert and Nicolas Mahut as both teams try to run their record to 2-0.

Follow Van on Twitter: @Van_Sias