Collins ran for 141 yards and two touchdowns and Arkansas won its fourth straight, 31-14 over ninth-ranked LSU on Saturday night.
Combined with Alabama's victory hours earlier, Arkansas (6-4, 4-2 Southeastern Conference) eliminated LSU (7-2, 4-2) from contention in the SEC West. Only two weeks earlier, the Tigers were unbeaten and ranked second by the College Football Playoff committee. They were No. 9 in the CFP this week after losing for the first time this season at Alabama on Nov. 7.
LSU running back Leonard Fournette had 127 yards from scrimmage and scored his 17th touchdown this season, but that may have done little to help his Heisman Trophy candidacy on a day when Alabama's Derrick Henry rushed for 204 yards and two scores.
Brandon Allen passed for 141 yards, including a 52-yard TD throw to Dominique Reed. Jared Cornelius added a 69-yard touchdown run in the fourth quarter that sent much of the Tiger Stadium crowd to the exits.
Arkansas, which entered the game with eight sacks all season, took down LSU's Brandon Harris five times.
The Tigers wound up with only 59 net yards on the ground while the Hogs rushed for 299, highlighted by Collins' 80-yard touchdown dash in the first half.
With LSU trailing by multiple scores much of the game, Harris attempted 35 passes, completing 21 for 271 yards and one touchdown. He also had a pass intercepted in the fourth quarter by D.J. Dean and lost a first-half fumble that set up an Arkansas touchdown.
LSU's Malachi Dupre had eight catches for 109 yards and a touchdown.
After a 1/3 start, the Razorbacks have won five of six with the only loss in that stretch coming at Alabama. The Razorbacks still have a chance to finish in a three-way tie for the SEC West if they and Mississippi win their final league games and if Alabama loses the Iron Bowl at Auburn.
Arkansas, which scored 170 points in its previous three games, raced to a three-touchdown lead in Death Valley, thanks to two big plays on offense and another on defense.
Reed scored first when he took a short pass from Allen in the right flat and bolted past LSU defensive backs Dwayne Thomas and Jamal Adams, then got a key block from Jared Cornelius near the right sideline to spring him for his 52-yard touchdown.
Collins went untouched until the final few yards of his longer TD, which made it 14-0.
Collins added his 5-yard score to make it 21-0, LSU's largest deficit this season. That scoring drive was set up when Harris, scrambling right, lost his handle on the ball while attempted to throw as he was hit by Dre Greenlaw on the LSU 15. Brooks Ellis recovered for Arkansas on the 11.
The Tigers didn't score until the last minute of the first half, and it took a fortunate deflection of Harris short pass off Travin Dural's hands and straight to Dupre in the back of the end zone.
AP college football website: www.collegefootball.ap.org