Promotion officials announced the bantamweight pairing on Monday.
LFC 20 takes place on May 31 in Corpus Christi, Texas.
Additionally, WEC veteran Antonio
Banuelos squares off with Jimmy Flick in
a flyweight co-feature, while former Bellator talent Robert
Villegas battles the unbeaten Justin Ledet
at 205 pounds.
Assuncao first appeared in the Octagon at UFC 64, losing to
Pellegrino via rear-naked choke in the opening frame. The
Brazilian left the promotion after a loss to Nate Diaz in
September 2007 and did not return until UFC 135 four years later,
where he took a unanimous verdict against Eddie Yagin.
The Hardcore Gym representative dropped a unanimous decision to
Pearson at UFC 141 in his last outing. Assuncao was expected to
make his promotional debut against Chris Jones on
April 12, but that bout was recently scrapped.
Pecero enters the matchup with Assuncao on a four-fight winning
streak. In his last outing the American Revolution MMA
representative submitted Louis Sims with
a first-round guillotine choke in November. Pecero has finished six
of his eight victories by way of knockout or submission.