Steve Johnson retires after 12 years on tour

(Photo credit: Jayne Kamin-Oncea-USA TODAY Sports)
American Steve Johnson ended his 12-year career on Sunday after losing in a doubles match in the BNP Paribas Open at Indian Wells, Calif.

Johnson and partner Tommy Paul lost a first-round match in straight sets to Wesley Koolhof and Nikola Mektic. Johnson, 34, announced the end of his career immediately afterward.

"It's kind of crazy to think that I've done this since I