The pair embarked on a task which will see them park their rumps on every seat in Wembley Stadium, a task which is expected to take up to five days to complete.
The football pundits are racing each other to be first to sit on half the seats in the 90,000 capacity venue for the thigh-burning Battle of the Backsides contest.
The duo have been kitted out with padded shorts to lessen the wear and tear on their rears.
They kicked off their competition this morning with Shearer taking an early lead, but Savage went on to turn it around and by this afternoon he was the top of the bots.
Before they began Shearer said: "Thirteen hours a day for five days is going to be one hell of a hard task. We've both been doing a bit of training, and judging by the size of Wembley it's a good job as well!"
And Savage said: "I don't think people realise the magnitude of the task until you're here in an empty stadium - honestly it's ridiculous. I think if we both get to the end and we've raised some money, we'll be happy."
The public can get involved by entering a competition at sportrelief.com/backsides, in which they can win tickets to see England at the World Cup in Brazil.