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Colonel Sanders is entering 2021 ready to rumble in the seemingly never-ending chicken sandwich wars.

KFC is finally updating its fried chicken sandwich after finding itself playing catch-up against rival chains’ sandwiches in recent years. The aptly titled “KFC Chicken Sandwich” features an extra crispy chicken filet placed on a buttered brioche bun and topped with pickles and spicy or classic mayonnaise.

The new sandwich is available Thursday in nine US cities: Chicago, Kansas City, Louisville, Portland, St. Louis, Sacramento, San Francisco, Seattle, and Tulsa. It will gradually roll out across KFC’s 4,000 restaurants nationwide over the next two months and fans can track the sandwich’s arrival on a special website.

The new "KFC Chicken Sandwich" makes it debut Thursday.

The sandwich costs $3.99 à la carte or $6.99 for a combination meal with fries and a medium drink.

KFC trialed the sandwich last June in 15 restaurants across Orlando. At the time, Andrea Zahumensky, KFC’s chief marketing officer, told CNN Business that the reformulated sandwich “boasts an upgrade of every single component” and she believes the chain is “now is going to be able to compete.”

The KFC Chicken Sandwich will replace the chain’s current sandwich, the “Crispy Colonel.”

“The ‘Crispy Colonel’ has a lot of fans, but we knew we could do better and it wasn’t good enough for us,” she said.

Early results for the new chicken sandwich are positive: Sales during the trial doubled KFC’s expectations, according to a press release. “Many customers hadn’t considered KFC as a part of the chicken sandwich conversation, but anyone who tastes this sandwich will know, without a doubt, that we’re playing to win,” Zahumensky said.

Owner Yum! Brands (YUM) reported mixed results for KFC in its third-quarter earnings. Global same-store sales fell 7%, but increased 9% in the US compared to the same quarter in 2019. The increase was attributed to a boost in digital and drive-thru sales, both of which will be central to its restaurant redesigns.

Chicken is a winner

Fried chicken sandwiches continue to be a popular item for fast food restaurants as customers crave affordable and comfort food.

Popeyes sparked the war when it first introduced the popular menu item in August 2019. Customers flocked to the chain and the sandwich sold out in less than two weeks. The company said at the time that the “extraordinary demand” took it by surprise and it was several months before it returned.

And it’s still popular: Sales at Popeyes restaurants open at least 17 months soared 17.4% globally in the third quarter of 2020 compared to the same period last year, thanks to the sandwich. Popeyes, which is owned by Restaurant Brands International (QSR), also controls Burger King and Tim Hortons. Popeyes was the company’s only brand to report a sales increase during the quarter ending September 30.

McDonald’s (MCD) is also rolling out three new chicken sandwiches next month: The Crispy Chicken Sandwich, topped with pickles and served on a potato roll; the Spicy Chicken Sandwich, which adds a spicy pepper sauce; and the Deluxe Chicken Sandwich, which comes with lettuce, tomatoes and mayo.

Like its peers, McDonald’s believes chicken is a good bet.

“Globally, the chicken category is almost twice the size of beef,” Joe Erlinger, president of McDonald’s USA, remarked in November. “It is growing faster and represents a significant opportunity,” he said. “Developing a reputation for great chicken represents one of our highest aspirations. We want customers to choose McDonald’s for chicken.”

Wendy’s added a new chicken sandwich to menus last fall. Its Classic Chicken Sandwich replaced the Homestyle Chicken Sandwich, which has been on Wendy’s menu for about a decade. Smaller chains, like Shake Shack (SHAK), Church’s and Whataburger, have also released variations of a chicken sandwich.

Of course, chicken has also proven to be a successful formula for Chick-fil-A, the 73-year-old chain that has a devoted fan base despite its controversial past. The privately held brand is steadily growing its reach, outselling chicken chains nearly twice its size. It has added about 1,000 locations and nearly tripled its sales over the last decade.

–CNN Business’ Danielle Wiener-Bronner contributed to this report.