The 33-year-old, who has emerged as one of the stars of the Games, booked his slot in the final today, with a dominant showing in his heat.
Returning to the Olympic Stadium track less than 13 hours after winning the 1,500m, the 33-year-old came in first ahead of Swiss rival Marcel Hug.
He said: “I had to keep remembering that there are two slots (to qualify) not three.
“I was a bit tired this morning but I got through. I got a bit more sleep than the first night (after his first gold medal). I just need to eat a bit more food tonight and I should be alright for the final.”
Weir confessed to having just two and a half hours sleep between his 5,000m title and 1500m heat, but revealed he had managed four and a half last night.
And after receiving a huge ovation as he returned an hour after his race to receive his 1500m medal yesterday, Weir said he was ready for today’s final.
He said: “I have to be confident now (for the 800m), I feel pretty good, but the T54 event is the toughest in the world.”
Hug, the world record holder over 800m, also sees Weir as the main contender for the gold tomorrow.
He said: “David Weir is racing very well, he is just flying, he has all the self-confidence and he has the crowd on his back so that makes him strong.”
The Briton is certainly riding the crest of a wave and goes into today’s final as the fastest qualifier from the three heats.
He now even has his own battle cry thanks to the werewolf howls his team-mates have developed, adapted from the 1970s rock song Werewolves Of London by Warren Zevon.