Issue when freezing Quaternion rotation in one axis?

Hi,

how can i freeze the rotation to an axis so that the character does not bend over to look at his target?

I have tried to copy the character's rotation in y or z, but the result is not what i would expect:

This is the wrong result : (the character is bending over)

4242

 var rot : Quaternion = Quaternion.identity;
 
 //in UPDATE
 var dir : Vector3 = vectorEndPoint - thisTransform.position; //vectorEndPoint = the ball; thisTransform = the character
             
 rot = Quaternion.LookRotation( dir ); 
 rot.eulerAngles.z = thisTransform.rotation.z;    //y or z        
 thisTransform.rotation = Quaternion.Slerp( thisTransform.rotation, rot, Time.deltaTime * 5 );

//or this way :

 var dir : Vector3 = vectorEndPoint - thisTransform.position;
 
 //TEST        
 thisTransform.rotation = Quaternion.Slerp( thisTransform.rotation, rot, Time.deltaTime * 5 );
 thisTransform.localEulerAngles = new Vector3(thisTransform.localEulerAngles.x, 0, thisTransform.localEulerAngles.z);

Would you know you to achieve this?

Thanks

---

SOLUTION:

 var newRotation = Quaternion.LookRotation( dir );
 newRotation.x = 0.0;
 newRotation.z = 0.0;
 thisTransform.rotation = Quaternion.Slerp( thisTransform.rotation, newRotation, Time.deltaTime * 5 );