FORMER Rangers manager Mark Warburton believes that the club must take a patient approach and lower their expectations in order to close the gap to league leaders Celtic.

The former Brentford boss left Ibrox in February 2017 with the club  24 points adrift of their rivals and behind Aberdeen on goal difference.

And Warburton, who was sacked by Nottingham Forest on New Year’s Eve last year, pointed to the financial gulf between the clubs as the biggest obstacle facing the Light Blues after another season of failing to keep pace with the Bhoys.

Read more: Walter Smith: Rangers are entering a crucial period in their history ahead of Ibrox managerial decision​

Speaking to Sky Sports, he said: "You have to recognise that Celtic have been in the Champions League for the past few years and have done well to get to the group stages and with that comes the financial rewards.

"All that does is increase the gap between Celtic and Rangers and every year you're fighting now to close that financial gap.

"The longer that Celtic are exposed to Champions League football, the greater the financial divide becomes so Rangers need the investment and they need to dampen expectation and recognise you've got to build the club back up because it is an outstanding club, it's a football institution and it was a privilege to manage up there.

"But you've got to be patient with it. Be honest with the fans and give them clear communications as they aspire to get the club back to the top of Scottish football but it will take time and it will certainly take investment."

The Gers eventually finished 39 points behind Brendan Rodgers’ side last season, but Warburton thinks the gap has closed this term as a result of Celtic failing to reach the same level they achieved in their Treble-winning campaign.  

He said: "I don't think it was more difficult, the keyword is expectation, Rangers with their history and tradition - the most successful club in the world, 54 league titles, the fans have suffered going down to the third division and are desperate for success.

"They crave success so going back up there the job in my mind was to consolidate in the Premier League, keep developing the squad and keep taking it forward but such is the expectation in Scotland that you'll always be compared to Celtic and that, last season particularly, was a big issue.

Read more: Walter Smith: Rangers are entering a crucial period in their history ahead of Ibrox managerial decision​

"The gap to Celtic, who had a record year in so many respects, and it was too much for people to stomach. Rangers is in their blood and to have that gap so wide was a painful time.”

He continued: "I was actually mocked by a couple of pundits, I referred to clubs regressing to their mean. They had an outstanding season last season and this year they've dropped many more points and all they've done is go back to an average season. So clubs or individuals have these outstanding seasons and it's how they maintain their standards in the season ahead.

"So all Celtic have done is regressed to their mean and the gap to Rangers is tighter but the key word in Scotland will always be expectation.”