You had to go back to 29 September 2016 for the last time Sir Gar had been beaten in the tournament, by Gower College, in a fixture that had little bearing on the outcome of the title last season. After that, they marched through the top pool with six wins in a row and then beat Coleg Y Cymoedd in the final.
The champions had opened up with a run of four successive victories this season before they came unstuck against a pumped-up CAVC side. Now they will have to beat Cymoedd in the re-run of last year's final when the two sides meet on 24 October to try to close the five-point gap at the top of the table.
CAVC were forced to come from behind to win, but they ensured that the sixth-minute score from Sir Gar hooker Dom Booth that outside half Llew Smith converted was wiped out by the break. In fact, two converted tries gave the home side a 14-7 interval lead and a titanic tussle ensued in the second half with no further points scored.
Cian Lewis-Hughes was the star of the show for Cymoedd as the second row grabbed two of his side's seven tries in a powerful 43-17 home win over Neath Port Talbot College at Sardis Road. Back row man Lloyd Gregory also scored twice and outside half Rhys Davies chipped in with four conversions.
The home side got off to a flying start with Gregory getting his first score after only four minutes. NPTC stayed in touch in the opening 20 minutes, trailing only 12-10 thanks to a Tiann Thomas-Wheeler penalty and conversion of Dewi Cross' try.
But by the break, Cymoedd had opened up a 26-10 lead as centre Joe Vickers, hooker Ieuan Morris and Lewis-Jones breached the visitors' line. Gregory's second try three minutes after the break extended the lead before Thomas-Wheeler converted his own try to cut the gap to 14 points.
But there was no holding the unbeaten league leaders as they made it five straight wins with further scores from Lewis-Hughes and replacement prop Matthew Iles.
Ysgol Glantaf is also in the mix at the top end of the table after their fourth win, a 24-8 win over arch-rivals Whitchurch HS. They are also on 19 points, equal with Sir Gar, and have home advantage over bottom but one team Bridgend College in their next game.
They ran in three first-half tries after making the two-mile trip up the road to Whitchurch and added a fourth five minutes into the second half to complete the scoring. Centre Jay Jones scored the first and last tries four minutes into each half and in between wing Tomi Owens and flanker Tom Callow also got in on the act.
There were two conversions from the boot of outside half Jake Hillman and the home side's points came from a Ruari O'Flynn penalty and a try from skipper and scrum-half Morgan James.
Gower College was beaten again as they fell to a 32-22 home defeat to Newport HS at Swansea Uplands. In a game of nine tries, it was the boot of the visiting outside half Iwan Burgwin that made the game safe as he landed three out of six kicks compared to one of out of four for Iwan Richards.
Burgwin's two conversions and a penalty ensured Newport HS stayed on course for their first win of the season. Gower was hit by a ferocious start from their visitors as they ran in four tries in the opening 21 minutes as hooker Brodie Coghlan and scrum-half Dafydd Buckland both struck twice.
Two conversions from Burgwin made it 24-0 in as many minutes and Gower was down and almost out. But the gallant home side knuckled down and managed to hit back with a try just before the break from back row man Dan Pritchard to stem the flow.
Things started to look even rosier when Gower ran in two tries in the opening four minutes of the second half through wing Luke Butler and flanker Evan Budge as the gap was reduced to nine points. Burgwin steadied the Newport HS nerves with a penalty, but then Pritchard struck again and this time Richards added the extras to make it a one-score game.
But Newport HS kept their nerve and closed the game out with a fifth and final try from full-back Morgan Richards
In the televised game on Tuesday night, Coleg Llandrillo picked up their second win of the campaign with a 22-7 victory at the Brewery Field over Bridgend College. They were trailing 7-6 after 20 minutes when centre Mathew Buchanan powered his way through the midfield and raced 30 metres to score at the posts.
That blockbusting effort changed the course of the game and put the north Walians on course for a timely victory. In the other fixture, Llandovery College registered their first win with a two-try, 14-13 home triumph over Pembrokeshire Rugby that included a great score from Toby Baldwin that set his side on course for victory.
Welsh Schools & Colleges League - Round 5
Bridgend College 7 - 22 Coleg Llandrillo
Cardiff & Vale College 14 - 7 Coleg Sir Gar
Coleg Y Cymoedd 43 - 17 Neath Port Talbot College
Gower College 22 - 32 Newport HS
Llandovery College 14 - 13 Pembrokeshire Rugby
Whitchurch HS 8 - 24 Ysgol Glantaf