LeBron James is stepping up his rivalry against Steph Curry on the court and in stores.

"Under Armour's biggest problem is that they only have one player in the game [of basketball]," Susan Anderson, senior analyst for B Riley FBR Inc., told TheStreet on Monday, July 2. "Even if [Steph] Curry is doing well, Nike, is so commanding, it's hard for [Under Armour] to gain an inch. [LeBron's move] can make it even more difficult.

James will sign with the Los Angeles Lakers for four years at $154 million, it was announced Monday. As James heads to the West Coast from the Cleveland Cavaliers to join one of the most well-known teams in the NBA, his star burns brighter and could rob shine from Steph Curry, San Franciso's Golden State Warriors phenom and Under Armour Inc.'s  (UAA) sole NBA athlete.

Nike Inc. (NKE) is a sponsor of James, one of many premier athletes the sportswear giant supports.

Curry signed with Under Armour, the Baltimore-based performance apparel company, in 2013 after Nike grossly mishandled its relationship with him, by mispronouncing his name, using another player's image in a slideshow presentation that was intended to feature him and low-balling him on the re-up contract by some $1.5 million. 

Under Armour swooped in and offered the two-time NBA Most Valuable Player a $4 million agreement. After two years, UAA extended its deal with Curry to 2024 and gave him an undisclosed ownership stake in Under Armour.

Under Armour was up slightly  mid-morning Tuesday, to $22.77, and is up 53% for 2018.

Yet, for now, Nike seems to have the advantage all around.