The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( Trefis) -- The competition in the single-serve coffee market is expected to intensify in the near future. According to Euromonitor, the worldwide sales of coffee, including fresh and instant, witnessed a growth of 17.5% approximately and reached $70.9 billion in 2011. The single-serve coffee segment witnessed an impressive growth of 31% and reported $5.8 billion in revenues. In the U.S., Green Mountain Coffee Roasters ( GMCR) is the dominant player with control over more than three-quarters of the U.S. market. However, Nestle is the leading player globally with a 35% market share followed by Sara Lee's ( SLE) Senseo brewers at 18%, and Kraft Foods' ( KFT) Tassimo at 8%.