(CNN) -- Those pesky drug testers.
Andy Murray received his OBE (Officer of the Order of the British Empire) from Prince William for his services to tennis but the man who ended Britain's 77-year men's singles drought at Wimbledon in July was in danger of being late at Buckingham Palace because drug testers came calling.
Under tennis' stringent 'whereabouts' rule, elite players have to tell testers where they'll be for an hour every day in case they want a sample.
And wouldn't you know, they showed up at Murray's door Thursday as the grand slam champion readied for his trip to one of the homes of British royalty.
"They turned up at my door at 8.20 a.m. and I had a taxi booked for half past eight," Murray, recovering from back surgery, told reporters. "I was a bit worried I was going to be late but the taxi did a great job in getting us here.
"It's part of the job but when you have a day like today you are looking forward to, it's the last thing you need."
Murray's moment of panic ended, he traded in his shorts and t-shirt for a smart, dark suit. He was allowed to bring three guests and chose -- not surprisingly -- his parents Judy and William and longtime girlfriend Kim Sears.
"I think they were quite proud," Murray told CNN. "My girlfriend is massively into anything royal. She was so excited about coming to Buckingham Palace for the first time.
"It was a great day for us."
Whereas Murray made history at Wimbledon and at the U.S. Open a year ago, it was the first investiture for new dad Prince William, who filled in for the 87-year-old Queen.
According to reports, Prince William chatted to Murray for nearly a minute -- one of the longest chats of the day.
"He asked me about my back surgery ... and how I was feeling after Wimbledon, when there was a lot of pressure on me," Murray told reporters.
"I teased him a bit as he had sent a note to me before Wimbledon wishing me luck and his wife had written me a letter afterward. Her handwriting was beautiful and I told him how fantastic it was compared to his.
"I have met him a few times before and he has always been very easy going. He seemed very relaxed today."
The decision to give Murray an OBE was actually made at the end of 2012. He won gold at the London Olympics and a month later ended Britain's 77-year grand slam men's singles drought in New York.
Murray won't play again this season following his surgery, thus missing out on the year-end championships in London in November.