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Michael Chang is playing in his 10th U.S. Open and enjoying his highest seeding ever , but the 24-year-old American had to overcome a case of the jitters Monday before winning his first-round match on opening day .
 Michael Chang, U.S. Open, American
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, else, organization, person 
Text: {0} 
Answer:
 Michael Chang, U.S. Open, American