Jack Sock will play for the Springfield (Missouri) Lasers in World Team Tennis after he was selected first in the preliminary draft.
He won gold in mixed doubles at the Rio Olympics and is the highest-ranked American man at No. 21 in the summer league.
John Isner, Eugenie Bouchard and Mardy Fish will head to the New York Empire. Andy Roddick and Sloane Stephens will join the Philadelphia Freedoms.
Venus Williams, Martina Hingis and Bob and Mike Bryan are returning to the Washington Kastles.
Team lineups will be completed at the March 14 draft in Indian Wells, California. Six teams will play 14 matches from July 16-Aug. 2. The top two teams advance to the finals Aug. 5.
The league, co-founded by Billie Jean King, enters its 42nd season.