Anyone know of a smooth way to join tweens?

using
var t = new mx.Transitions.Tween(myMC,"_x",undefined,0,100,20)
t.onMotionFinished = function(){
new mx.Transitions.Tween(myMC,"_y",undefined,0,100,20)
}

leaves a pause…Id like to not have that pause, anyone know a slick trick to avoid the pause?