What’s growing faster than e-commerce in the United States?

Pickleball, a paddle game that’s a blend of tennis, badminton and pingpong played on a miniature tennis court with a lower net. The number of places a person can find a pickleball court in the United States grew 27% from August 2015 to August 2016, according to the USA Pickleball Association. That growth rate outpaces e-commerce, which grew 14.6% last year, per U.S. Commerce Department estimates.

Situated at the crossroads of pickleball and e-retailing is PickleballCentral.com and its cofounder, David Johnson. The e-retailer’s sales of pickleball equipment and clothing have grown 40-50% annually for the past five years and are in the “eight figures,” Johnson says, or at least $10 million. The merchant began designing and selling pickleball-themed T-shirts online in 2006 after Johnson couldn’t find any such tees for sale online. He and his wife wanted to buy her parents—avid pickleball players—tees as a gift.

“We hired a graphic designer to do a design for us and printed through CafePress,” Johnson says. “It was really a hobby, and then it started to take off a bit. Then we saw that no one else was doing a good job selling the equipment online, so we thought why not do that?” CafePress Inc., No. 249 in the Internet Retailer 2016 Top 500 Guide, lets consumers upload designs that can be applied to a variety of products, such as T-shirts and coffee mugs.

PickleballCentral.com grew to the point where Johnson was able to leave his technology job to work on the business full time in 2009, and his wife left her job soon thereafter to join him. The business eventually moved out of the Johnson’s home and into a nearby warehouse, and the company is now the largest reseller of pickleball equipment in the world, Johnson says.

The e-retailer, based in Kent, Wash., is for all practical purposes at the epicenter of pickleball. Pickleball originated in the 1960s on nearby Bainbridge Island, where one of the game’s founders had a dog named Pickles. Last month PickleballCentral.com acquired the Seattle company Pickle-ball Inc., a manufacturer of pickleball equipment. The purchase adds product manufacturing capabilities and a large wholesale business, Johnson says, calling it a great fit.

The majority—about 80%—of PickleballCentral.com’s sales happen on-site, Johnson says, and the e-retailer gets more than 40% of its traffic from search engines, according to web analytics data from SimilarWeb. PickleballCentral.com is the top organic search result returned by Google in a search for “pickleball equipment,” beating matches from the much larger Dick’s Sporting Goods Inc. and Amazon.com Inc., which take the second and third spots in results. Dick’s is No. 62 in the Top 500; Amazon is No. 1.

“We work SEO, but the key thing is customer satisfaction,” Johnson says, noting the e-retailer’s 30-day return policy, same-day shipping and great reviews from customers. “We try to really be there for the customer, and make it easy for them to make an online purchase.”

PickleballCentral.com generates about 20% of its sales through its storefront on the Amazon.com marketplace, where, if a consumer follows the Amazon search result for pickleball equipment, he will see numerous products listed for sale by PickleballCentral.com under the “best sellers” and “top rated” categories. PickleballCentral.com also sells a small amount on eBay Inc., Johnson says.

Johnson says he thinks PickeballCentral.com has a high profile online because it got in early and was well-positioned as interest in the game caught fire. “For a long time it was hard to find pickleball equipment in regular sporting goods stores, so players had to buy it online. Now that is starting to change,” he says.

There are more than 2.5 million pickleball players in the United States, according to the Sports & Fitness Industry Association, and more than 12,600 courts to play on. Schools are introducing pickleball to kids as part of gym class, and older consumers are flocking to the game as well. A retirement community in The Villages, Fla., has more than 100 pickleball courts for residents.

“The sport is just growing, and we’ve been able to piggyback on the growth of the sport,” Johnson says.