Taking part in a personal tennis class with Roger Federer is the ultimate dream for many fans, but this is the last thing you'd want to do if given such an incredible opportunity.
Federer gave a few punters some tennis lessons ahead of his charity exhibition match against Andy Murray in Glasgow on Wednesday.
With about 10 people on court, everyone was happily playing a benign rally when Federer popped up a slow looping lob to one bloke at the net.
The man's eyes lit up as he went for the big smash, and boy did he nail it.
The only problem? He hit Federer right in the back.
A number of his fellow punters gave big cheers of delight, but some weren't particularly impressed.
As you can see in the video above, the man was actually somewhat chastised for trying to hit a winner rather than keeping the rally going.
Federer himself laughed off the incident and jokingly told the punter: "Don't do that!"
Later in the evening, Federer beat Murray in three sets in the Scot's first match since he limped out of the Wimbledon quarter-finals in July.
The World No.2 sent the Scottish fans wild when he donned a kilt and still held serve in the second set.
The funds raised from the match went to Unicef and other local charities.
Murray is targeting a return to competitive tennis at the Brisbane International in January in the lead-up to the Australian Open.
"My hip felt pretty good, not perfect yet but it’s going in the right direction," Murray said after the relaxed one-hour, 40-minute hit with Federer.
"I’ve got eight weeks until my first tournament of next year and hopefully I’ll be there."