A vascular closure system includes a suture and an anchor assembly. The anchor assembly includes a first anchor portion having a plurality of petal members automatically expandable from a retracted position for delivery through a vessel puncture in a vessel, and an expanded position when deployed within the vessel. The anchor assembly also includes a second anchor portion connected to the suture and positioned distal of the first anchor portion within the vessel. Withdrawing the suture pulls the second anchor portion against the first anchor portion to contact the first anchor portion against an inner surface of the vessel adjacent to the vessel puncture. The vascular closure system may also include an automatic compaction assembly that automatically compacts a sealing member against the anchor assembly to seal closed the vessel puncture upon withdrawal of the vascular closure system.