Cabrera Bello bounced back from an opening bogey with birdies on four of the next five holes, and then added four birdies on the first six holes of the back nine.
Bradley, who started the day in second place behind Spanish overnight leader Rafa Cabrera Bello, turned in six birdies to go with a pair of bogeys.
"I woke up Sunday and I couldn't really walk", Day, ranked No. 11 in the world, told Golf Channel's Will Gray.
British Open champion Francesco Molinari made one of two aces on the day - the other belonged to D.A. Points - and was among those at 69.
The 34-year-old from Las Palmas, who teed off on the 10th, nearly capped a superb performance with an ace at the par-three second, drilling his tee-shot to within a foot of the pin.
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He said such progress was "leading to a day where we are launching American astronauts on American rockets from American soil". The Crew Dragon never loses its built-in escape rockets, which eliminates that danger and simplifies the system overall.
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However, the 18-year-old has had a limited play time for Chelsea although his impact on the game has been significant anytime his is introduced.
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The Indian high commissioner will also engage on urgent issues not only with Pakistan but with diplomats of other countries in Islamabad .
"Playing with Sam is always a pleasure, not because he's the grandson of Arnie but because of how nice of a guy he is, " Cabrera Bello said.
Jason Day's Players Championship campaign is in serious doubt after withdrawing mid-round on day one at the Arnold Palmer Invitational at Bay Hill in Florida.
"And I think sometimes I'm too much of a fan of the game because I know exactly who has won the Grand Slam, and I know exactly the people I would be putting myself alongside". The top three players not already exempt from the top 10 at Bay Hill will get into Royal Portrush.
"My back was sore when I was practicing from Tuesday to Saturday, and I was going to practice on Sunday, but I woke up and couldn't really walk or sit in the vehicle".
"I've been making sure I get my driver turning over (right-to-left) as that's something I've struggled with the last couple of years at the Masters".
Day was one of just three Australians to start the week, Aaron Baddeley the best of the remaining two after 18 holes with a 2-under 70 to be T15.