Scans have revealed the 24-year-old has fractured the third metatarsal in his left foot, and he will go under the knife on Tuesday and be out for an indefinite period.
After winning their first four games, the Lions have lost five straight to fall outside the top eight. Adcock's injury means the running half-back will join Jared Brennan (ankle), Jamie Charman (ankle), Josh Drummond (knee) and Daniel Merrett (hamstring) on the sidelines.
Adcock gathered 20 possessions in Sunday’s clash with Adelaide before injuring his foot in the second quarter.
Despite Adcock's setback, Lions coach Michael Voss has predicted the Lions can turn around their season against competition heavyweights Collingwood at the Gabba on Saturday night.
Voss said there were more positive signs in his players’ attitude and commitment at the ball in Sunday's loss to the Crows.
“We’ve actually got some genuine hope coming into this week,” Voss said.
“They’ve lost that little bit of faith, that little bit of trust, and they’ve slowly been able to build that up over the last couple of weeks.
“Those issues of confidence come to the fore in big games like this.”
The Lions had 85 tackles to Adelaide's 58 at AAMI Stadium, a statistic Voss said was a sign of his players’ improved attack on the ball and the man.
“We had an extraordinary amount of tackles,” Voss said.
“It wasn’t the fact that we were chasing; what I’ve seen return is our intent to want to be able to get after the opposition. Now it’s about being able to ensure that we can finish our work.”
Accuracy in front of goal again proved costly against the Crows, with three Lions players missing relatively simple shots in the tense final quarter.
Voss said while players will work on their kicking efficiency at training, it’s likely to improve as their confidence levels return.
“They should draw confidence from the fact we are getting our chances,” Voss said.
“We were showing very good skill levels at the start of the season, so basically for us it’s the finishing touches.
“You’ve just got to be able to back yourself in and be able to do it; free the shackles a bit and want to take those kicks.”
Voss praised Brendan Fevola for his five-goal effort, which showcased some of his freakish scoring talents from a range of angles.
He said the full-forward was stung by a poor performance in round eight against Geelong.
“The important facet that he adds to our forward line group is his pressure and, when the ball hits the ground, his second efforts,” Voss said.
"If he has the intent to get after the ball once the ball is on the ground, he can kick those general play goals that we’ve seen him kick.”
The Lions have appointed Rob Kerr as national talent manager, replacing the long-serving Graeme 'Gubby' Allan, who moved to the new GWS outfit in February.
Kerr, the former CEO of the AFL Players Association, will be based in Melbourne and look after recruitment, talent identification and salary cap negotiations.
“He’s a very strong person, has some very considerable relationships within the AFL sector,” Voss said.
“To have someone like that with that sort of extensive experience and thoroughness and attention to detail I think is going to set us in good stead for the next period.”
