Steven Gerrard admits he is not satisfied with second best as he strives to make Rangers real challengers next season.

The Light Blues have guaranteed the Ladbrokes Premiership runners-up slot after beating Aberdeen with two James Tavernier penalties.

Their 2-0 Ibrox win – Gers' first against the Dons in Glasgow this season – also further delayed Celtic's wait for the title as they closed the gap on the champions-elect to nine points with nine still available.

But Gerrard admits he will not be happy until his side are putting up a proper fight for the league crown.

"Second place is not enough," said the former Champions League winner after seeing his side end Aberdeen's four-year run as the 'best of the rest'.

"It is progress and I know the club is moving forward in certain areas. We are improving and looking stronger but there is still a lot of work and improvement to do.

"We need more quality to help the 11 and we need to continue to improve our discipline and our injury record.

"If we make those three things happen, I'm confident we can be more competitive next season."

On Friday, Gerrard had accused Derek McInnes' team of trying harder against Rangers than their other opponents.

But with a raft of injuries to key men, the Dons did well just to stay in the game until the hosts got the breakthrough after 48 minutes.

Joe Lewis had frustrated Rangers with some stunning first-half saves but Lewis Ferguson's trip on Nikola Katic gave Rangers a penalty which Tavernier tucked home for his 15th goal of the season.

And he added another with 10 minutes left when Katic again went down in the box, this time claiming to have been struck by a flailing arm from Andrew Considine.

The Aberdeen defender was stunned by referee Don Robertson's decision and his frustrations were compounded as he was shown a second yellow card.

Tavernier showed no mercy as he fired home again from the spot.

There was still time for former Rangers captain Lee Wallace – out of contract this summer – to get a late standing ovation in tribute to his loyalty in the wake of the club's financial implosion seven years ago.

The left-back has been a peripheral figure under Gerrard but the boss, who confirmed Rangers are "on the cusp" of announcing the signing of Motherwell's Jake Hastie, said: "Lee deserved his spot in the 18.

"He's had one of his strongest weeks, training wise. He got 45 minutes against Liverpool under-23s and was outstanding. He was in on merit. It's important people don't think it was anything to do with sentiment.

"We played so well in open play I'm surprised it took two penalties to win the game but their keeper's been magnificent today.

"The second penalty's a bit soft, probably not a penalty, and I hope the kid gets the yellow card overturned. But the first one's a penalty because he stands on his foot."

McInnes told Sky Sports that Katic should "hang his head in shame" over his theatrical fall following his tussle with Considine.

And in his post-match press conference, he added: "With the second penalty – words fail me how that can be given.

"It's a terrible decision which had a huge impact on the end result. Rangers were good in spells and they are a good side who are playing with confidence.

"But there's no doubt the second goal effectively killed the game as it put us down to 10 men.

"The reaction from the Rangers player was bad enough but for the referee to be kidded by that and give the penalty is really disappointing.

"From then on they would have been as well putting the lights out as the game was over.

"It's mad that we can't appeal it and Andy will miss another game against Celtic next week because of it."