Custom footwear is a big part of sneaker culture today and it's a trend that even athletes are taking with them on game day. As if having your own Player Exclusive wasn't enough, athletes are enlisting customizers to put in work on their footwear that goes beyond simple color-blocking enhancements. It's a trend that's been all the rage in the NFL as of late, but Nike isn't having it.

According to TMZ, several Nike-endorsed NFL athletes have received letters warning them against customizing their football cleats. TMZ got a hold of the letter and it includes, "Nike views third-party customization (or post-embellishment) of Nike footwear to be a violation of the contract, triggering Nike's right to immediately terminate the contract."

Nike's beef is that customizing its footwear obstructs the visibility of the Swoosh, which essentially goes against what an endorsement deal is all about in the first place.

The letter continues, "Nike Football values its endorsement relationship with you and presumes you were unfamiliar with these previsions in your Nike Football Contract. However, please know that Nike expects that you will observe the requirements of our contracts."

Sole Collector also reported on this potential fiasco and was told by sneaker customizer Mache, "I think they're more concerned about the Swooshes getting covered up." (You can read the rest of their report here.)

Does this mean no more custom Nike cleats on the field? Looks like you'll have to tune in this Sunday to find out.

[via TMZ and Sole Collector]