Invicta Fighting Championship got hit with a pair of late changes for tonight’s sixth event while trying to get fighters official at Friday’s weigh-ins.

On just one day’s notice, Kathina Catron (3-2) will step up to fight Livia Von Plettenberg (1-1) on the preliminary card of Invicta FC 6. Catron replaces Cassie Robb (0-1) in an odd set of circumstances.

Robb was scheduled to meet von Plettenberg in an atom weight bout. But when von Plettenberg weighed in at 113 pounds for the 105-pound bout, the fight was scrapped with the extreme weight difference. Instead, despite missing weight for her contracted fight, von Plettenberg is the one who will remain on the card – and move up to a flyweight bout against Catron.

Promotion officials late Friday confirmed the news from MMARising.com.

Invicta FC 6 takes place today at Ameristar Casino Hotel in Kansas City, Mo. The event airs on pay-per-view in North America, and international viewers can watch via an online pay-per-view stream, each for $14.95.

Catron just a week ago picked up a second-round TKO win over Summer Atherton in Nebraska. That win snapped a two-fight skid that included a 12-second submission loss by flying armbar to Rose Namajunas at Invicta FC 5 in April. That fight was Catron’s Invicta FC debut.

In January, von Plettenberg, from Austria, lost her promotional debut with a unanimous decision setback to Joanne Calderwood at Invicta FC 5. She made her pro debut in June 2012 with a TKO win. She reportedly underestimated the weight cut to get to atomweight, where she would have fought Robb.

Robb, meanwhile, now has Saturday night off. The 22-year-old Wyoming-based fighter was looking for her first pro win after losing her promotional debut at Invicta FC 4 in January with a second-round submission to Laura Sanko.

With the change, the new Invicta FC 6 lineup includes:

MAIN CARD (Pay-per-view, 9 p.m. ET)

PRELIMINARY CARD (Ustream, 7 p.m. ET)

For the latest on Invicta FC 6, check out the MMA Rumors section of the site.

(Pictured: Livia von Plettenberg)