Chinnor had to fight hard to maintain their unbeaten run against Barnstable away, eventually winning by five points.
The Thame team have now won their first ten games of the season and face similarly unbeaten Bournemouth this weekend in the first title show-down of the year.
On Saturday Barnstable struck first with an unconverted try which seemed to kick-start Chinnor.
They hit back with a try after some good work from the pack and then added to the scoreline with a pair of penalties scored by James Cathcart after good Chinnor pressure.
Before the break the visitors extended their lead to 16-5 and were beginning to coast but Barnstable came out of the blocks firing in the second-half with an early try.
Cheered on by home support they then added two penalties to take the lead, 18-16.
Chinnor dug in and on 59 minutes Matt Goode crossed the tryline to make it 23-18.