Marshall retained her WBO middleweight belt as unified champion Shields watched on in Newcastle
Marshall handed Hermans the first stoppage loss of her career with a stunning left hook in the final seconds of the third round.
It was an emphatic message to send to Shields, who was watching at ringside in the Utilita Arena, ahead of a projected meeting later this summer.
The rivalry between Marshall and two-time Olympic champion Shields has been brewing since the Englishwoman beat the American at the World Amateur Championships in 2012.
The Hartlepool-born Marshall told Sky Sports: “There’s no one else in the way of me and Claressa – it’s me and Claressa in the summer now.
“I know Claressa can’t handle my power. I believe I severely hurt Claressa.”
Contudo, Shields insisted she was unimpressed by Marshall’s performance, dizendo: “I went the distance with Femke four years ago, early in my career. [Marshall] is gonna have trouble with me, and she’s definitely not gonna knock me out.
“She’s definitely not [the biggest women’s puncher]. Femke was able to make her miss, and I’m ten times faster than Femke, so what do you think I’m gonna do?”
Mais cedo no sábado, Marshall’s promoters Boxxer announced the respective signings of British Olympic champion Lauren Price and bronze medallist Karriss Artingstall.