John Cook, an 11-times winner on the PGA Tour, has been appointed as an assistant to United States captain Fred Couples for this month\'s Presidents Cup in Australia, the tour said on Tuesday.American Cook will replace basketball great Michael Jordan, who withdrew from the role due to the ongoing labor dispute and player lockout in the National Basketball Association (NBA).Jordan, a majority owner of the NBA\'s Charlotte Bobcats, had initially been appointed as one of two assistants, along with PGA Tour veteran Jay Haas, for the Nov. 17-20 competition at Royal Melbourne.\"John has been a friend of mine since we broke in together on the PGA Tour in the early 1980s,\" Couples said in a statement. \"Having achieved success at the highest levels in the golf world, I value his opinion greatly.\"I would like to thank Michael for his significant contributions, both as a captain\'s assistant and his role as ambassador for the Presidents Cup.\"While the team will miss his friendship, spirit and leadership, we certainly understand the complexity of his current team obligations.\"Jordan, who served as an honorary captain\'s assistant to Couples at the 2009 Presidents Cup, said: \"It is with regret that I have decided to cancel my trip to Australia later this month.\"With the NBA labor situation unsettled, as the majority owner of the Charlotte Bobcats, I feel it is necessary that I remain in the country. It was an honor to have been chosen by Fred Couples to serve as a captain\'s assistant.\"The Presidents Cup is a Ryder Cup-style competition which pits a U.S. team against a line-up of International players from countries outside Europe.The U.S. won the trophy in 2009 for the sixth time in eight editions.