Rangers bungled a major chance to secure qualification to the knockout rounds of the Europa League after only managing a 1-1 draw against Aris at Ibrox.
The Scottish giants could now need to win at Real Betis in two weeks to qualify for the next round if Sparta Prague beat Aris in Cyprus.
Former Rangers striker Miller insisted that it was all very flat from the Glasgow giants on a big night in Europe and conceded that towards the end of the game, the crowd were more aware of the importance of a winner than Rangers for their European hopes.
He stressed that it is going to be extremely difficult for Rangers to get something in Seville in two weeks and they could rue the points they dropped against Aris in their group.
Miller said on BBC Radio Scotland: “It was all pretty flat, to be honest with you.
“There was no real push towards the end of the game to go and get that winner.
“It seemed the fans in the stands and even us in the commentary box were more aware of what it means and how much that goal was needed, in terms of qualification tonight.
“It is going to be really tough to go to Betis and potentially they might need to win the game to actually qualify.
“It’s all to do in a couple of weeks’ time for Rangers to make sure that they qualify.
“To drop four points to Aris, with the greatest of respect, in this group is just not good enough.”
Rangers did beat Real Betis at Ibrox earlier in the season in the Europa League.
