NOTRE DAME The skinny Under coach Kevin Corrigan, the Fighting Irish have become a national powerhouse, qualifying for their seventh straight NCAA tournament as the No. 4 seed. They played for the NCAA title in 2010 and are making their third semifinal appearance. The seniors are a combined 49-13. Key to advance Defense and depth — the Fighting Irish (13-2) play a packed-in man-to-man defense that relies on switching, proper defensive spacing and forcing low-percentage, weak-angle shots. Offensively, they rely on a star but benefit from contributions from three midfield units. Nine players scored in the first-round win against Yale, and eight found the net in the 12-10 win over No. 5 seed Virginia in the quarterfinals.