Like the Gingham Dog and Calico Cat, Heinz ketchup and French’s mustard have side by side in the condiments aisle sat for more than a century.

Now, they are squaring off for what promises to be a terrible spat. Heinz, the Great Dane of ketchup, has retooled its much less well-known mustard with plans to chip away at French’s dominance.

Not to be outdone, French’s, the Savannah cat of mustard, is muscling its way into the ketchup lineup, convinced that it can steal market share.

“Oh, I don’t think it’s a war so much,” said Elliott Penner, president of the French’s Food Company, which is owned by the Reckitt Benckiser Group, which also owns brands like Clearasil and Woolite. “I think it’s just about doing a better job of making ketchup.”