Larkin, a point guard out of Miami who was selected with the 18th overall pick, needed surgery after breaking the ankle in the Mavs' summer league team's final practice before leaving for Las Vegas.
There isn't a firm timetable for when Larkin will start playing games.
"I felt good out there," Larkin said. "I don't have my quickness back yet, but that'll come in the next couple of practices. Hopefully within the next couple of weeks -- a week, week and a half, I'll be back being able to play."
Mekel, a 25-year-old Israel native, has averaged 4.3 points, 3.3 assists and 13.3 minutes in the Mavs' first three games. Veteran Devin Harris, who is recovering from toe surgery, still hasn't been cleared for any on-court work.
The 5-foot-11, 176-pound Larkin, the ACC player of the year last season and son of baseball Hall of Famer Barry Larkin, reminds the front office of former Mavs point guard J.J. Barea, a sparkplug whose prowess as a pick-and-roll ballhandler was a key component to Dallas' 2011 championship run.
The surgery on Larkin was performed July 16. He had hoped to be cleared by the beginning of training camp, but the Mavs took a cautious approach with the rookie, who called the process "frustrating."
"It's a step," Mavs coach Rick Carlisle said of Larkin's first practice. "He's picking things up. For the first day of live practice, he did well."