The invention provides a method of providing an endovascular bypass. The method includes the steps of inserting an elastic needle carrying a guidewire adjacent an ostium via a catheter and extending the needle through a branch vessel wall. The method continues by extending the needle through the extravascular space and inserting the needle through a main vessel wall to create an opening. The needle is retracted, leaving the guidewire in place. A bypass stent graft is inserted along the guidewire to provide a pathway between the branch vessel and the main vessel, and the inserted bypass stent graft is expanded. The branch vessel is occluded between the ostium of the bypass stent graft and the main vessel, and a main stent graft is inserted in the main vessel proximate the opening in the main vessel wall.