Then Smith hurt his hamstring, giving Green a chance.
"Coach tells us all the time - make the most of our opportunities and be ready," Green said.
Green certainly made the most of his nine carries Saturday night, rushing for 134 yards and two touchdowns in a 63-27 win over Eastern Michigan. The highlight was a 99-yard scoring run in the second quarter that put the Razorbacks ahead 35-0.
And Green wasn't the only runner who shone in Smith's absence. Knile Davis also rushed for two touchdowns on a night Arkansas substituted liberally.
"We blocked well and our running backs did a nice job," coach Bobby Petrino said.
Green transferred from Southern California, saying he wanted to be closer to his grandmother, who was sick. The NCAA allowed him to play immediately, without sitting out a year. Smith, who rushed for 1,000 yards last season, is still the team's best rushing threat, but the 6-foot-2, 248-pound Green has been used in short-yardage spots with mixed results.
Smith missed his second game in three weeks Saturday, so Green, Davis and freshman Ronnie Wingo Jr. handled most of the running. On first down from the Arkansas 1-yard line, Green found a hole and then outran the defense to the left sideline. He appeared to run out of steam a bit at the Eastern Michigan 40, but a couple defenders came up empty trying to tackle him.
Eastern Michigan entered the weekend ranked No. 1 in the nation against the pass and dead last against the run. The Eagles are still last against the run, but they fell to No. 4 against the pass.
Ryan Mallett completed all 10 of his attempts in the first half and threw for a pair of second-quarter touchdowns to Joe Adams. He finished 14 of 16 for 248 yards and three TDs.
"I thought Ryan executed really well," Petrino said. "He was focused and practiced hard all week."
Adams, back after missing three games because of a mild stroke, caught three passes for 109 yards to end a scary month on a positive note.
"I knew I was going to be back at some point," Adams said. "I appreciate life more in general now. I don't take life for granted and I'm blessed to still be here on this field and back out there playing with my team."
Tyler Wilson relieved Mallett in the second quarter and again toward the end of the game, going 5 of 11 with an interception. It was a sloppy finish for the Razorbacks, who allowed Eastern Michigan's Kyle McMahon to throw three touchdown passes long after the outcome was decided.
Petrino said he wanted to remove his starters earlier than he did - but Eastern Michigan started scoring.
"Our plan was to get the ball back and get our ones out," Petrino said. "Unfortunately our defense did not hold up their end and we had to leave our ones in there."
Arkansas was coming off back-to-back losses to Florida and Mississippi. This was the first of four straight home games for the Razorbacks, who face South Carolina next weekend.
"We're ready to get back into (Southeastern Conference) play," wide receiver Lucas Miller said. "We know that these are the games that count and (Saturday's) game gives us a lot of confidence going into next week's game against South Carolina. We know we're going to have to be ready to play next week, but we got over the hump today and it felt great."