HOLDERS Chinnor 2nd reached the semi-finals with a battling 28-20 victory over Henley 2nd at Kingsey Road.
Henley hit back to lead 12-8 at half-time, but could not hold on.
Adrian Hales scored the opening try for Chinnor, with Sam Angell adding a penalty.
Tries from Ryan Sheehan and Ed Stembridge, the latter converted by Liam O’Neill, put Henley 12-8 ahead.
Angell converted try No 2 from Trevor Powell before he and O’Neill exchanged penalties for 18-15.
Dave Hughes completed Chinnor’s try tally, Angell converting and adding a penalty.
Simon Perry went over for Henley’s third try, but it was not enough.
With Henley and Oxford Harlequins already knocked out, Chinnor are big favourites to make it four Oxfordshire Cup wins in a row.
They will host Witney in the last four on either February 2 or 3.
Witney received a walkover from Grove, who were unable to field a side at Hailey Road.
Wallingford will visit Oxford University Greyhounds in the other semi-final.
Greyhounds hammered Banbury 50-26 at Bodicote Park on Friday night.
Sam Wareham, Will Boardman and David Cooper-Parry each scored try braces for the students.
Ben Brooks and Phil Bell also crossed over, with Will Dace converting five.
Wallingford held on to see off Alchester 17-11 at the Hithercroft.
Tom Miles kicked Alchester ahead with a penalty, but Wallingford hit back when Fraser Hunt raced in from 40 yards.
Phil Dawes converted, while Miles’s second penalty made it 7-6 after the break.
Wallingford moved the ball wide for Ben Selwood to score, Dawes converting.
Alchester’s Charlie Surman went over from close range, but they could not make late pressure tell.