Stepping in for Vemola to fight Leben is Derek Brunson, a Strikeforce veteran with a record of 9-2. This news was broken via mmajunkie.com.
The fight between Leben and Brunson will take place on the main card, which comes to viewers via pay-per-view.
Leben will be returning from a year-long suspension, as he failed a drug test last year. That drug test came after his loss to Mark Munoz, which was adding insult to injury.
Prior to the suspension and loss, Leben had won four of his last five, including knockouts of Wanderlei Silva and Aaron Simpson, as well as a triangle choke win over Yoshihiro Akiyama.
His only loss in that span came to Brian Stann, who knocked him out at UFC 125.
As for Brunson, the four-time Strikeforce veteran started off his career with nine straight wins, which included seven first-round finishes. He has defeated notables Nate James and Lumumba Sayers in Strikeforce.
He enters the UFC on a two-fight skid. He lost a close, controversial split decision to Kendall Grove in the regional circuit and then suffered a quick knockout loss to Ronaldo Souza.
That was followed up by a bid to make it on The Ultimate Fighter 17. He was accepted onto the show's cast, but that would be blocked by Showtime, the distributor of Strikeforce.
It looks like Brunson will make out alright, as he will make it directly to the UFC instead of going through the TUF house. However, he has a tough road ahead of him, as Leben is a heavy hitter.