Lopez had won 10 straight fights before making his UFC debut in September when he lost a unanimous decision to Justin Edwards at UFC Fight Night 25.
Sadollah fought twice in 2011, winning one and losing one. He had a submission win over DaMarques Johnson in March, but most recently, dropped a unanimous decision to Duane Ludwig at UFC on Versus 5 in August.
Kuiper is a 22-year-old Dutch fighter skilled on the ground and on the feet. Six of his 11 wins have come by knockout, four by submission. Kuiper knocked out his last three opponents in the first round.
Natal is 1-1-1 inside the Octagon since making his UFC debut in Sept. 2010. He last fought in August, winning a unanimous decision over Paul Bradley at UFC 133 in Philadelphia.
The Super Bowl weekend fight card is headlined with a welterweight title fight between reigning champion Georges St-Pierre and former Strikeforce champ Nick Diaz. For the full UFC 143 line-up as it stands see our Upcoming Events page.