KEY BISCAYNE, Fla. -- Juan Martin del Potro's latest comeback from an injury is off to a slow start, and he's OK with that.
Playing his first match since Jan. 15, Del Potro lost Thursday to Vasek Pospisil 6-4, 7-6 (7) in the first round of the Miami Open.
"I don't feel frustrated," Del Potro said. "I have to take the positive things on my comeback. The score doesn't matter for now."
Del Potro had been sidelined with a lingering left wrist injury. The 2009 US Open champion had wrist surgery a year ago and played in just four tournaments in 2014, and his ranking has fallen to No. 616.
Rustiness showed in the second set, to the disappointment of a partisan crowd rooting for the Argentine. He served at 5-4 and was broken. He double-faulted holding a set point, lost another set point and double-faulted again on the next-to-last point.
Del Potro converted only one of six break-point chances and hit just nine winners to 36 for Pospisil, a Canadian ranked 60th.
"I didn't serve well in the special moments," Del Potro said. "But now I'm OK. Just playing the tournament and being here means a lot for me."
Del Potro said he felt fine physically after the match. He said his wrist is not yet 100 percent but that it's improving week by week.
"It doesn't matter how long it takes me to be at the top again," he said. "I just wanted to play tennis and without pain."
In other results, Americans Steve Johnson and Ryan Harrison lost, as did former Australian Open runner-up Marcos Baghdatis.
Martin Klizan won and will face No. 1 Novak Djokovic in the second round Saturday night. Rafael Nadal and Andy Murray are among those playing their opening matches Friday.