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 - Get Report) sole NBA athlete.

Nike Inc. (NKE - Get Report) 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.