Under Armour's (UA - Get Report) debut at mid-tier department store Kohl's (KSS - Get Report) has started on the right foot. 

Kohl's CEO Kevin Mansell said on a conference call Thursday that sales of Under Armour products beat "very aggressive" expectations during the first quarter. Strength was seen across all product categories, according to Mansell. 

Under Armour products arrived at 1,100 Kohl's stores on March 1. 

The news may help temper some concerns on Wall Street about the impact of Under Armour's foray into a more affordable venue. 

UBS noted in late April that because of Under Armour being in Kohl's, it triggered increased markdowns of Under Armour gear in more premium retailers. Susquehanna also voiced concern.

"Within men's and women's apparel, 50 percent (maybe a bit more) of the [Under Armour' styles [at Kohl's] are also available at Dick's Sporting Goods (DKS - Get Report) ," wrote analyst Sam Poser. 

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