Levein is under pressure with Hearts sitting one point above bottom place in the Scottish Premiership after Saturday's 0-0 draw with Livingston.

But the Edinburgh side are missing at least seven first-team regulars.

"I'm sure once Craig gets them back and into the team, they'll start to pick up points," Robertson told BBC Scotland.

"Their confidence seems a bit low, but they are missing an entire team of established first-choice players."

Former Hearts striker Robertson, now managing Championship side Inverness Caledonian Thistle, suggested the return of Scotland forward Steven Naismith, centre-backs Craig Halkett and John Souttar, winger Jamie Walker and midfielder Peter Haring would ensure the Tynecastle outfit would "be a force again".

"It's not an easy situation and sometimes people looking in think it's an excuse, but when you've got that amount of quality on the sidelines, it's difficult to replace at times," said Robertson, who was speaking after being inducted into the Scottish football hall of fame.

Levein 'can pull up the barricades'

Robertson believes that former team-mate Levein will cope with the criticism aimed at him in the meantime.

"At a club like Hearts, expectation is always high, but Craig can handle that because he has broad shoulders," he said. "You've seen the flack he's been getting from all aspects, but he'll handle that in his own way.

"He can pull up the barricades and he can be quite combative at times, and I'm sure that is what he'll do. As long as he can shield his players and protect them as much as he can, he'll do that until he gets all his players back and tries to get the right results.

"Craig is a big boy and he understands that a club like Hearts and fans like that want results. But what I can tell you without fear of contradiction is that, in Craig's mind, it's his belief that he will be the man to turn that around and get the results that the fans desperately crave."