Germany’s Jan-Lennard Struff is heartbroken after withdrawing from the singles competition at the Paris Olympics due to injury concerns. Struff withdrew before his second round match on Tuesday, handing Frenchman Corentin Moutet a walkover. He told dpa he made the decision to avoid another prolonged absence due to hip problems. “I think everyone who knows me knows how much I enjoy playing for Germany. But the risk of ruining everything again was clearly too great,” Struff said. Last year, the German number two had to take several months off due to hip issues. He said he felt the problems again…