As important than in 760's seems really hard.
On the other hand, important in the Middle East region is doable.
Al-Mustazhir could benefit from a crusader sucess in 1101. Seljukids would be politically weakened and discredited, and the Abbassids could impose themselves as leaders there.
The Seljuk sultan Muhammad I could be killed during the riot of Bagdad in 1111, making the caliphe able to take the power.
Now, you'll need a bit of luck for uniting the syrian principalities, but at least Mesopotamia is doable in a first time.