What has been billed as the most meaningful women’s match in British boxing history is, at the very least, in limbo.

The death of Queen Elizabeth II on Thursday and the United Kingdom’s official mourning period very well could cause a postponement of the showdown between Claressa Shields and Savannah Marshall. Shields (12-0, 2 KOs), of Flint, Michigan, and Marshall (12-0, 10 KOs), of Hartlepool, England, are scheduled to headline an all-women’s card Saturday night at O2 Arena in London.

Shields, 27, and Marshall, 31, participated in a press conference Thursday afternoon in London. The death of Queen Elizabeth II, who was 96, was announced later Thursday, which left promoters of the Shields-Marshall card to deal with its potential postponement.

The event had not been officially postponed as of Thursday night in the UK. BoxingScene.com has learned that all of the fighters on the card will weigh in Friday morning, just in case they are granted permission to move forward with the event.

Sky Sports is supposed to televise the Shields-Marshall show Saturday night in the UK and Ireland. ESPN is contracted to stream it in the United States on Saturday afternoon.

Shields, a two-time Olympic gold medalist and three-division champion as a professional, held out hope Thursday night that she’ll still get her chance to avenge her only loss as an amateur or professional boxer by beating Marshall in their 12-round, 160-pound title unification fight. The hard-hitting Marshall defeated Shields on points, 14-8, at the 2012 AIBA Women’s World Boxing Championships, but Shields hasn’t lost a boxing match since that loss to Marshall 10 years ago.

The Shields-Marshall undercard is supposed to feature another title unification bout between Mikaela Mayer and Alycia Baumgardner.

Mayer (17-0, 5 KOs), of Colorado Springs, Colorado, and Baumgardner (12-1, 7 KOs), of Bingham Farms, Michigan, are contracted to fight for Baumgardner’s WBC and IBO belts and Mayer’s IBF and WBO 130-pound championships. Their 10-round co-feature would remain part of the Shields-Marshall undercard if it needs to be rescheduled.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.