The debut of one UFC newcomer is on hold, and another first-timer will step in for him at UFC 173 later this month.

With Doo Ho Choi (11-1 MMA, 0-0 UFC) out of his fight against against Sam Sicilia (12-4 MMA, 2-3 UFC) with an injury, Sicilia now will face Aaron Phillips (5-0 MMA, 0-0 UFC). UFC officials recently made the new booking official.

UFC 173 takes place May 24 at MGM Grand Garden Arena in Las Vegas. The main is a bantamweight title fight between champion Renan Barao and T.J. Dillashaw. The main card airs on pay-per-view following prelims on FOX Sports 1 and UFC Fight Pass.

Phillips, from Louisiana, trains with the likes of UFC veteran Tim Credeur and has three first-round knockout stoppages to his credit. His two most recent wins for regional promotions have been by decision, however.

Sicilia, a veteran of Season 15 of “The Ultimate Fighter,” will be looking to get back on track after a January submission loss to Cole Miller at UFC Fight Night 35. This past November, the Washington native snapped a two fight skid when he stopped Godofredo Pepey in the first round at UFC Fight Night 32 in Brazil.

After appearing on “TUF 15,” he won his seventh straight fight when he knocked out fellow castmate Cristiano Marcello at the TUF 15 Finale. But then he suffered setbacks against Rony Jason at UFC 153 and Maximo Blanco at the TUF 17 Finale.

Choi, from South Korea, was looking to extend his nine-fight winning streak, which dates back more than three and a half years. For Japan’s Deep promotion, he has won five straight fights by knockout or TKO, which is how he has finished eight of his 11 career victories. The bout against Sicilia was to be the 22-year-old’s first fight outside of Asia.

The official UFC 173 lineup now includes:

MAIN CARD (Pay-per-view, 10 p.m. ET)

Renan Barao vs. T.J. Dillashaw

for UFC bantamweight title

Daniel Cormier vs. Dan Henderson

Jake Ellenberger vs. Robbie Lawler

Takeya Mizugaki vs. Francisco Rivera

James Krause vs. Jamie Varner

PRELIMINARY CARD (FOX Sports 1, 8 p.m. ET)

Michael Chiesa vs. Francisco Trinaldo

Tony Ferguson vs. Katsunori Kikuno

Chico Camus vs. Chris Holdsworth

Mitch Clarke vs. Al Iaquinta

PRELIMINARY CARD (UFC Fight Pass, 6:30 p.m. ET)

Anthony Njokuani vs. Vinc Pichel

Aaron Phillips vs. Sam Sicilia

Jingliang Li vs. David Michaud

For the latest on UFC 173, stay tuned to the UFC Rumors section of the site.

(Pictured: Sam Sicilia)