Shields won a unanimous decision over Ema Kozin in Cardiff on Saturday to retain her IBF, WBA and WBC middleweight championship and edge a step closer to facing WBO titleholder Marshall.

Marshall mockingly yawned and pretended to fall asleep during Shields' performance - they then rowed afterwards.

"If you perform like that against me, I'll absolutely wipe the floor with you," Marshall warned.

Shields shouted: "I'm not scared of you. You didn't come to America. I came here!"

Marshall: "Wind your neck in."

Shields: "I'm chasing you."

Marshall: "People were walking out [during your fight!] It was embarrassing."

Shields had said: "The girl I want is Marshall. That's why I'm here. She knows that."

Tempers flared as Shields got into Marshall's face and the rivals had to be separated.

Promoter Ben Shalom said: "It's up to me to make the biggest women's fight of all time."

Marshall must first defend her belt against Femke Hermans on March 12, live on Sky Sports.

Shields had totally dominated her opponent Kozin and came close to securing the stoppage through her quick-fire punches and body shots.

In the final rounds Shields was able to abandon her own defence and hunt for the knockout but Kozin bravely hung on.

"I thought there were plenty of moments where the referee should have stopped it," Shields said.

"I give myself an A-. The only thing I didn't do was get the damn knockout!

"She took six, seven, eight shots without responding. I thought her corner might have stopped it."

Sky Sports Boxing schedule

Saturday February 19 in Manchester
Amir Khan vs Kell Brook
Natasha Jonas vs Ewa Piatkowska - WBO super-welterweight title
Frazer Clarke's pro debut

Saturday February 26 in Glasgow
Josh Taylor vs Jack Catterall - undisputed super-lightweight titles
Nick Campbell vs Jay McFarlane - Scottish heavyweight title

Saturday March 5 in Fresno
Jose Ramirez vs Jose Pedraza

Saturday March 12 in Newcastle
Savannah Marshall vs Femke Hermans - WBO middleweight title

Sunday March 20 in New York
Edgar Berlanga vs Steve Rolls
Keyshawn Davis
Xander Zayas