A superb last-gasp Tristan Corpe try saw Chinnor complete an unlikely comeback to keep their unbeaten record in tact at Davey Field.
Shelford led 19-3 at half time, a score which reflected their dominance during the first 40 minutes.
Aki Lea was the first on the score sheet after just 3 minutes and two further converted tries through Will Lawson, on his debut, and Steve Smith saw the score race to 19-3, James Cathcart slotting a penalty in return for the visitors.
But Chinnor came out for the second half fired up and hooker Ed Vickers showed great pace to touch down under the posts within a minute of the restart. Cathcart converting.
Shelford hooker Francis Ambrose then saw red on his debut for a second yellow card offence.
Chinnor immediately took advantage with full back Matt Mountford splitting the defence to touch down in the corner. The Cathcart conversion brought Chinnor within 2 points.
And on the final play of the game Chinnor ran the ball from their own 22 through a number of passes and it was winger Corpe who was on hand to sprint the final 40 metres to secure a hard-earned victory.
(Report from The Rugby Paper)
This victory puts Chinnor in 2nd position in the league with 3 wins from 3 starts this season.