Just when Michael Owen was coming on the TV cameras caught the tooth brusher red handed. What's next, are we going to see people with their electric razors shaving away while the take in an EPL game? I wouldn't be surprised if we see a full stadium of fans with their toothbrushes over the next couple of weeks as a joke.
Sharp-eyed internet users posted the clip on YouTube and within hours it had been watched by more than 1,000 people.
BBC Radio 5 Live presenter DJ Spoony also spotted the fan, who bizarrely was wearing dark glasses.
He asked on air: 'Why has he got a toothbrush in the stadium?
'And more importantly, why is he brushing his teeth in the stadium?'
Co-host Gabriele Marcotti answered jokingly: 'Dental hygiene.
'Every time you eat something, you should brush your teeth afterwards.
'You were taught that, right? You should be flossing too, I would add.'
Spoony went on: 'So you're in the football stadium, you've had your pie, you brush your teeth. I mean where do you rinse, or gargle?'
The fan later answered Spoony's appeal to phone in and explain his strange behaviour.
He said he had not had time to brush his teeth before setting off for the game and was wearing dark glasses because his ex-girlfriend was there and he is "a ladies' man".
Chelsea won the top-of-the-table clash 1-0, thanks to a 76th minute goal from captain John Terry.