American Robert Kendrick, who served an eight-month suspension for doping, is back on court again. On Tuesday, the 31-year-old fell to teenager Jack Sock, 2-6, 7-6 (1), 6-3, in the first round of the $100,000 Challenger in Dallas. He also lost in the first round of the Honolulu Challenger two weeks ago.

Kendrick tested positive for the banned stimulant methylhexaneamine at 2011 Roland Garros, and claimed he was unaware there was a banned substance in the pill, which he took to combat jet lag.

He was hoping to make the 2011 U.S. Open his last tournament, but his appeal to the Court of Arbitration for Sport was only reduced by four months.

Kendrick was unclear after the decision as to whether he would make a return, but given that his partner was due to give birth and he lost a substantial amount of potential earnings, his return is not surprising.—Matt Cronin