With the students out-of-action, second-placed Bargoed had the chance to close the gap at the top to two points heading in to the final weeks of the season.
But they were smashed by rivals Bargoed in a high-scoring thriller, which leaves the race for second wide open.
The hosts ran-in seven tries through Ashley Norton, Rhys Humphreys, Ricky Cochlin, Adam Cullen, Lee Williams, Gareth Dare and Jamie Howells.
Llanharan replied through a brace-apiece by Elliot Foiles and Lee Thorne, but they were well beaten in the end, 52-31.
Caerphilly were relegated after they were destroyed by Blackwood at Glan yr Afon Park. Gareth Price and Mark Birkraer braces were among the nine Blackwood tries as they sealed the visitors’ fate with a 61-7 triumph.
Things are getting tight for the second relegation spot, and Ystrad Rhondda took a huge step towards safety with a fine 35-17 victory over
Tredegar.
Shaun Robson bagged a double, and Nathan Hughes, Alex Webber and Mazin al-Azlani also touched-down for the hosts.
They are now level on points with Beddau, who played out a thrilling 32-32 draw with Merthyr.
Lewis Jones and Viv Owen both crossed twice for Beddau as they sealed what could turn out to be a precious two points.
Bedlinog can now begin to look ahead after confirming their safety with a 26-17 victory against Rumney. Martin Luckwell, Phil Cocharan and Martin Jones scored the hosts’ tries.
Builth Wells pulled off one of the results of the season in Division One West as they beat third-placed Narberth, 19-17.
Tries by George Jenkins and Andy Garrod for Builth were cancelled out by scores for Michael Thomas and Nick Clancy for Bonymaen, who led 17-16 with two minutes remaining. It was then left to Builth star John Thurston to slot over a late penalty and seal a famous victory for the hosts.
That result also saw Whitland confirmed as second place finishers, despite them being given a lesson in running rugby from champions Tonmawr.
Scores from Juan Socino (2), Tal Selley, Gareth John and Darryl Harvey, plus a penalty try, saw Tonmawr to a 45-20 victory at the Memorial Ground.
Bridgend seem to be heading for safety after they beat Carmarthen 32-12. Tom Grabham, Lloyd Peers and a Matthew Morgan double saw them to an important bonus-point triumph.
Felinfoel sealed their safety with a 43-23 victory at relegated Cymllynfell and Bridgend Athletic beat Corus 44-24.
