Car: '87 300SDL 121K

During a tire rotation today, I broke off a lug in the left rear wheel. The head sheared off, and left the shaft and body in the hub. I'm in real trouble if there's a flat, eh?

The lug was tightened by a lug wrench last time, so no pneumatics figure into the failure.

Any thoughts on getting this out? So far, all I've been able to think of is drilling it out, and since the wheel won't come off the car, that would have to be "freehand". I need a better answer. Please advise.

Tom Kanis
87 300 SDL 121K