BILLINGS, Mont. - Valdiron de Oliveira had hoped to return to competition this weekend.

After failing a concussion test in Dallas, though, the No. 1 rider was deemed unfit to ride by Dr. Tandy Freeman. Oliveira is officially listed as probable for next week's Built Ford Tough Series event in Nampa, Idaho.

Oliveira was injured in the third round of the Mohegan Sun Invitational in Uncasville, Conn., when he was kicked between the shoulders by Main Event. The impact with the dirt fractured his left eye socket and resulted in a concussion.

It wasn't Valdiron de Oliveira's broken eye socket that kept him out of competition this weekend, it was the concussion.

He normally does not wear a helmet, but is expected to wear a helmet and protective facemask when he returns to competition in the two remaining BFTS events prior to the summer break.

Oliveira will need to undergo surgery for the fracture, but is waiting until the swelling subsides. He has decided to compete in the meantime.

He has been battling J.B. Mauney atop the world standings for much of the season, but World Champion Silvano Alves is now within 1,167.25 points of the top spot.

Mauney is in Billings, and for the second event in a row will be competing with his right hand after undergoing surgery to fix his left riding hand, which was broken when his left palm was stepped on last month in Kansas City, Mo.

PBR WEEK: Mayor Tom Hanel declared it PBR Week in Billings yesterday at a bull weigh-in at the Rimrock Auto Arena. Watch the KULR report here.

THE BIG MATCHUPS: The fifth of nine PBR 15/15 Bucking Battles will be held immediately following Round 1 on Friday. The PBR 15/15 Bucking Battle features the Top 15 riders in the world competing against the 15 highest-ranked bulls at the event for an additional purse of $21,000.

The bulls were each randomly assigned a position from 1-15. The riders were then matched with their bulls based upon their own current rankings in the BFTS standings. BFTS points will be doubled in the PBR 15/15 Bucking Battle, with the winner receiving 200 points and second place receiving 180 points, continuing on a graduated scale to 20 points for 10th place.

Points earned count toward the BFTS standings, but do not count toward determining the event winner in Billings. Money earned counts towards qualification for the World Finals. If a rider fails to make a qualified ride, he does not receive any points or money.

This week's matchups include: No. 17 Harve Stewart vs. Straight Jacket; No. 16 Robson Palermo vs. David's Dream; No. 15 Stormy Wing vs. Red River; No. 13 Luke Snyder vs. Carrillo Cartel; No. 12 Caleb Sanderson vs. Great White; No. 19 Kody Lostroh vs. Mac-Nett's Southern Wine; No. 10 Justin Koon vs. Cooper Tires Grey Ghost; No. 9 Fabiano Vieira vs. Party All The Time; No. 8 Renato Nunes vs. Buckey; No. 7 Austin Meier vs. Smackdown; No. 6 Guilherme Marchi vs. Pandemic; No. 5 Marco Eguche vs. Chocolate Thunder; No. 4 Mauney vs. RMEF Gunpowder & Lead; No. 3 L.J. Jenkins vs. Unser Racing Bull and No. 2 Alves vs. Cowboy Casanova.

Stewart, Palermo, Lostroh and Sanderson were put into the draw because of injuries to Oliveira (1), Douglas Duncan (11), Ty Pozzobon (14) and Chris Shivers (18).

PAST WINNERS: Past 15/15 Bucking Battle winners include: Oliveira, 94 points, Sacramento, Calif.; Snyder, 90 points, Albuquerque, N.M.; Duncan, 90.75 points, Indianapolis; and Meier, 90.25 points, Uncasville. Top scoring bulls include: Asteroid, 47.5 points, Sacramento; Bushwacker, 46.5 points, Albuquerque; and Asteroid, 46.75 points in Indianapolis, and 46.5 points in Uncasville.

TOP 10 SCORES FROM PAST 15/15 BUCKING BATTLES: 94 Oliveira, Buckey, Sacramento; 92.25 Meier, Shepherd Hills Trapper, Sacramento; 91.5 Mauney, Larry the Cable Guy's Git-R-Done, Sacramento; 90.75 Duncan, Bad Blake, Indianapolis;  90.25 Snyder, Black Attack, Sacramento; 90.25 Aaron Roy, Mac-Nett's Southern Wine, Sacramento; 90.25 Meier, Delco, Uncasville; 90 Snyder, Party All the Time, Albuquerque; 90 Oliveira, Jr. Bonner, Albuquerque; 90 Mauney, Ragin JT, Kansas City.

INJURY UPDATE: According to Freeman's latest injury report, in addition to Oliveira missing this week's event, Ryan Dirteater is out of competition due to a concussion sustained at the Mohegan Sun Invitational. Pozzobon is out of competition in Billings due to a recurrent right-knee MCL sprain sustained at the Mohegan Sun. Dirteater and Pozzobon are both listed as probable for next week's event in Nampa.

Shivers is out for 8-12 weeks with a right (free arm) clavicle fracture sustained in Albuquerque. Pistol Robinson is out with a surgically repaired broken right femur and a surgically repaired broken left tibia. Pete Farley is out with a traumatic brain injury. Tyler Thomson is out with a surgically reconstructed left knee.

McKennon Wimberly is out with a traumatic brain injury sustained last year.

DUNCAN RECOVERING: Duncan is out of competition for the three BFTS events leading into the summer break. On Wednesday, the Texas native underwent successful surgery to repair a hip injury. In a text message the following day, he wrote, "It went good!" A complete update on his progress will be posted on www.pbr.com next week.

BIG SKY COUNTRY NATIVE: Montana native Mesa Pate said it's an honor to haul bulls to what is essentially a hometown BFTS event for her. Among the bulls she'll have in Billings will be Cowboy Casanova, whom she refers to as her baby. He will be matched up with Alves in the 15/15 Bucking Battle.

Montana native Mesa Pate is bringing Cowboy Casanova to Billings. Pate blogs regularly at PBR.com.

Pate said she was 8 years old when her parents brought her to Billings to see the BFTS event in person for the first time. In an interview during a bull weigh-in with local media, Pate said she knew then she wanted to one day haul bulls to the BFTS as a contractor.

TV GUIDE: The 15/15 Bucking Battle will be broadcast in its entirety on CBS at 1 p.m. ET this Saturday, May 5. Please check local listings.

Round 1 will be broadcast in its entirety live on YouTube at the Professional Bull Riders Channel this Friday, May 4, at 10 p.m. ET. CBS Sports Network will broadcast action from Round 2 at 10 p.m. ET this Saturday, May 5, with an encore airing at 2 a.m. ET on Sunday, May 6. CBS Sports Network will broadcast action from Round 3 and the Built Ford Tough Championship Round at 6 p.m. ET this Sunday, May 6. There will be encore airings on Sunday at 9 p.m. ET, and on Monday, May 7, at 9 p.m. ET.

Veteran broadcaster Craig Hummer will provide the play-by-play. Color commentary will be provided by nine-time World Champion and PBR co-founder Ty Murray. Chute and dirt-level interviews will be handled by Leah Garcia.