Nike will review the newly created running shoe category, which includes men's training, football, basketball and running shoes.
It said that the recent announcement about a category alignment within its business, provided it with an "opportunity to re-evaluate" its creative resources and partnerships.
Dean Stoyer, US media relations director at Nike, said: "As our business grows, our brand communications must also continue to evolve to meet an increasingly challenging marketplace."
It is not known whether this will affect the global Nike account, worth around $500m (£259m), or its US account, which is worth around $200m.
The move is a blow for Wieden & Kennedy. Nike has worked almost exclusively with the agency for more than 20 years. Dan Wieden, the agency's founder, was the man who came up with the iconic tagline: "Just do it".
However, over the last 10 years, Nike has given small portions of its business to other agencies. It gave the US creative assignment for its Niketown chain to Leap Partnership in 1995. In 1997, it handed a $50m creative budget to Goodby, Silverstein & Partners for Niketown retail creative work, without the account going to pitch.
Crispin Porter & Bogusky, the Miami-based agency and US hot shop, is believed to be in strong contention to pick up some of the business. It is reported to have been in talks with Nike for months, but this has yet to be confirmed by either party.
Despite moving part of its account from W&K, Nike was keen to stress that the sports firm would continue its close relationship with the agency.
Stoyer said: "You will certainly continue to see Nike working with W&K. Nike has always looked to a variety of partners in various areas of demand creation to keep things fresh and on the cutting edge. With an interesting challenging marketplace we are even more committed to staying out in front of where and how our customers are engaging with the brand."