Most burger chains like Red Robin don’t pay much attention to pizza chains like Donatos—one specializes in pizza, the other in burgers. It’s like two highways that never intersect, or two restaurant chains with little overlap.

But Columbus-based pizza chain Donatos hooked up with Greenwood, Colorado-based burger chain Red Robin in October 2019 to test out a partnership, offering pizza in 25 Red Robin locations in Cleveland, Arizona and North Carolina.

The early returns were so favorable that the two chains expanded the agreement to cover 100 Red Robins, or 20% of the chain’s footprint. For Donatos, a chain of 161 pizza shops, the agreement has expanded its name recognition west of the Mississippi and on the West Coast.

Red Robin, like many casual dining chains, has been facing revenue pressure. Red Robin’s fourth quarter earnings (released February 25), its total revenue was $302.9 million, a decrease of 1.2%, though comparable restaurant revenue spiked 1.3% compared to last year.

Moreover, Red Robin has been facing pressure from a private equity firm Vintage Capital Management, which has been trying to gain seats on its board, to shake up the company.

Jonathan Muhtar, chief concept officer at Red Robin, explained that the synergy between the two chains works because “pizza fits right in with our classic American favorites like burgers, wings and shakes.”