Britney Spears has been pushed to do too much too soon and is buckling under the pressure, according to insiders.

Just months after her stay in a psychiatric unit, the singer has launched a full-scale comeback - and is said to be feeling burnt out already.

And with a gruelling two-month world tour scheduled to kick off in March, Britney's management won't be easing up on her any time soon.

"It is too much for her," a source tells OK!

"They packed her schedule too tight and now they're trying to find free time."

But sources close to the star are adamant she has what it takes to pull off a show-stopping tour next year: "She is focused.

"Everything is coming together."