Fanatics is a little-known company that helps drive the sports merchandising industry with its online store and by operating the Web sites and filling orders for sports partners. The holidays are its Super Bowl, World Series and Final Four all rolled in one.

In the fall, many of the most popular sports are in action like the NFL, college football, baseball’s World Series as well as the start of the NBA and NHL seasons. Throw in the busy holiday shopping season, and you’ve got a recipe for huge sales.

“This is a bit of a perfect storm where we have all the major holidays,” said Doug Mack, CEO of Fanatics.” The world of sports is exciting right now.”

On a typical day, Fanatics ships around 70,000 orders. On a day like Cyber Monday, the first Monday after Thanksgiving, that number swells to as much as 700,000.

This year is going well. On Cyber Monday, for example, sales were up 20% from the previous year, according to a spokesman.

“We’ll do more than half of our business in this quarter alone,” Mack said.

Fanatics declined to divulge any details about its revenue. But Internet Retailer, which e-commerce sales, ranked Fanatics No. 42 on the list of top online U.S. retailers with sales of $990 million in 2013. It’s also the top-ranked sports retailer on the list, while Nike ranked No. 64 and Dick’s Sporting Goods came in at No. 72. Fanatics would say that it expects to ship more than 30 million orders this year.

The site is a sort of Amazon of sports merchandise. It stocks over one million items along with powering the Web sites of all the major sports leagues, a number of television broadcasters like NBC Sports and individual collegiate and professional teams including the Seattle Seahawks, the Yankees and the Boston Celtics.

Like on the athletic field, competition in sports merchandise can be fierce. Fanatics competes against fellow retailers like Amazon, Nike, Adidas and Dicks Sporting Goods, sports gear stores like Lids, and the sports memorabilia giant Steiner.

Fanatics, based in Jacksonville, Fl., has five warehouses across the country for handling orders. To cope with the holiday rush, it hires around 5,000 temp workers on top of its full-time staff of about 1,600.

As with many retailers, sales by Fanatics via mobile devices is growing quickly. Orders from people using smartphones, for example, have doubled from last year to exceed those from desktop computers, according to the company.

The website serves as a barometer of what fans are interested in most on any given day, Mack said. Teams playing in the World Cup or World Series inevitably get a boost in orders. But sales can dip for players who get injured or who are not playing well.

Earlier this year, it was the “summer of Jeter,” Mack said. Jeter, the Yankees star, retired after a storied baseball career, which could only mean one thing for Fanatics: His products were top-sellers from April through the summer.

But when trouble emerges, like with the dual NFL scandals involving Ray Rice and Adrian Peterson for domestic violence, Fanatics steps back and takes the lead from the leagues. Mack explained that products featuring those two athletes were quickly pulled from sale.

“We’re definitely in line with how the league wants to handle disciplinary action,” Mack said.

And for the fairly new CEO, the transition to Fanatics has been a smooth one, he told Fortune. He started at the company in April after heading online home decor site One Kings Lane for four years. In all, he’s spent 17 years in e-commerce.

Mack’s focus going forward? He prefers to focus on the opportunities, not the challenges.

“Our team is doing a good job, and I’m feeling more in opportunity mode than in challenge [mode],” he said.