One of the most interesting revelations from Popeyes’ chicken sandwich mania was how it affected competitors. Market intelligence firm Numerator ran some data that looked at the figures four weeks pre-launch and two weeks post.

What it found was pretty staggering, although not surprising. The data suggested roughly 30 percent of Popeyes’ new chicken sandwich buyers were purchasing crispy chicken sandwiches at other quick-serves in the weeks before. Share of wallet data after launch indicated a shift in chicken sandwich spend across several leading players.

Popeyes and Chick-fil-A saw their stakes rise. McDonald’s was among those that lost ground, going from 17 to 15.1 percent.

You can break that down in terms of who was buying the sandwich, per Numerator. More Gen Z (3.3 versus 2.6 percent), millennial (20 versus 19 percent), and Gen X (43 versus 35 percent) guests were purchasing the product compared to Popeyes’ overall base. It also brought in high income (46 versus 38 percent) customers compared to typical traffic.

Restaurant Brands International chief executive Jose Cil said recently the sandwich addressed one of Popeyes’ historic hurdles: Trial has long been a key obstacle to purchase intent. Cil said 65 percent of the country hasn’t tried Popeyes. But internal research proves that first-time users stick around. So there’s ample runway to gain.

That’s also why the chicken sandwich lifted business for bone-in chicken, tenders, beverages, and even desserts this past quarter.

Naturally, this stirred a same-store sales spike for Popeyes’ as comps boosted 10.2 percent in Q3—its strongest showing in two decades.

Yet while Chick-fil-A played an active role in the drama, and enjoyed an awareness lift of its own from the social back and forth, McDonald’s has been noticeably absent. Executives said in October that the increased competitive pressure around chicken was affecting mix. “I think it’s fair to assume with everything going on in the quarter with chicken that we did go a little bit the opposite way on chicken,” EVP and CFO Kevin Ozan said.

That could change, however.

McDonald’s announced via social platforms Sunday it’s testing a Crispy Chicken Sandwich in Houston and Knoxville, Tennessee. The chain’s version features a fried chicken filet served on a buttery potato roll, with butter and pickles on top. McDonald’s is also offering a deluxe sandwich with tomatoes, lettuce, and mayo.

A McDonald’s spokesperson told CNBC the test would run from December 2 through January 26.

The chain’s chicken efforts have been a conversation starter for months. McDonald’s franchisees pushed over the summer for a Southern-style edition to keep pace with Chick-fil-A’s rapid ascension. The brand has nearly doubled its U.S. store count in the last 12 years, hitting 2,400 units and $10 billion in total systemwide sales by year-end 2018. And its chicken sandwich hasn’t changed since Chick-fil-A debuted 53 years ago in Atlanta.

For comparison, McDonald’s closed 2018 with 13,914 domestic units, a decline of 122 year-over-year. Nearly all (13,229) were franchised as the brand pushed (in millions), $38,524.05 in total systemwide sales. Average-unit volume was $2.769 million. Chick-fil-A’s stores reported $4.167 million per location.

McDonald’s National Owners Association, the independent franchisee group formed in 2018, wrote in a July email that the chain should make a chicken sandwich its top priority.

The brand has McNuggets and a McChicken Sandwich. And it introduced a Spicy BBQ Chicken Sandwich and Glazed Tenders LTO in September.

However, McDonald’s hasn’t tested an offering similar to Chick-fil-A’s hero item since 2018. Then, the brand piloted its “Ultimate Chicken Sandwich” to more than 160 Washington locations.

McDonald’s also enjoyed a highly touted Buttermilk Crispy Tenders launch in late 2017 that resulted in some stores running out of product. It returned six weeks later to less fanfare.

The brand had a Southern Style Chicken Sandwich, served on a hamburger bun with a fried chicken filet and pickles, but it was discontinued in 2015 after a 10-year run.

Chicken for breakfast?

Business Insider reported in late October that McDonald’s plans to launch chicken at breakfast in January, according to internal documents reviewed by the publication.

McDonald’s did not reveal details about what the product might be. It’s tested McChicken McMuffins, Chicken McGriddles, and McChicken Biscuits recently, and currently serves chicken options at breakfast in roughly half of its U.S. stores.

But doing so systemwide could play a key role in what promises to be one of quick service’s most hotly contested battlegrounds in 2020. With Wendy’s taking another crack at the daypart, in addition to Burger King and Panera’s renewed pushes, McDonald’s will have more competition than ever during an occasion it once dominated. Five years ago, per Euromonitor, the top earner in fast food held 17.4 percent of the morning battle. Last year, it was 14.7 percent.

The segment, despite recent challenges, still mixes roughly 25 percent of McDonald’s sales, which is significantly higher than most brands. Taco Bell is about 10 percent. Wendy’s hopes to reach that figure, too, and is spending $20 million upfront to get there.