In "The Most Dangerous Game", why was Zaroff glad that it was Rainsford who had come to the island?

Coincidentally, General Zaroff had heard of Rainsford before and was quite familiar with his reputation as a successful hunter.  Upon arriving at his mansion, Rainsford's first meeting with Zaroff shows evidence of this in the way that Zaroff compliments him, saying, "It is a very great pleasure and honor to welcome Mr. Sanger Rainsford, the celebrated hunter, to my home."  He continues this by explaining how he knows who Rainsford is: "I've read your book about hunting snow leopards in Tibet, you see."  He later deems Rainsford a worthy opponent when he informs him that he (Rainsford) will act as his prey in that evening's hunt, saying, "I drink to a foe worthy of me at last."  Zaroff's passion for the sport of hunting is so great that he actually longs for prey that may actually beat him and escape.  He has gotten so good that it has become too easy, and so he is happy to meet Rainsford, knowing that his knowledge of the "great" game of hunting will ensure an exciting and complex hunt that evening.