GWYR booked their place in the Welsh Schools' Under-16 Cup quarter-finals with a 17-5 win at home to neighbours Gowerton.
Gwyr were on the front foot early on and opened the scoring when centre Rhodri Wall sliced through the defence before passing to co-centre Rhys Gealy, who touched down beneath the posts for a try converted by fly-half James Davies.
On 25 minutes a spell of concerted pressure by the visitors, with hooker Marcus Besley and prop James Tanner prominent, was rewarded with a try for flanker Kieryn Lewis.
On the stroke of half-time the hosts stretched their lead. An initial thrust by centre Gealy was denied by an excellent cover tackle from Gowerton full-back Keelan Giles but, when possession was recycled, Gwyr fly-half Davies crossed for a try he again converted.
Early in the second half, the hosts stretched their lead with a Davies penalty, but in the final quarter, spurred on by captain and man of the match Richard Keefe, Gowerton pressed for another score.
Lock Jack Petherbridge dominated the line-outs and Gowerton dominated field position. However, Gwyr's defence was unflinching and they held out to deservedly progress to the last eight.
Meanwhile, Gowerton's first XV fell to a 14-10 home defeat against Amman Valley in the final game of their Welsh Schools' League programme.
The hosts took the lead in the fifth minute when a well-constructed move allowed centre Sam Pridgeon to cross for a try that fly-half Mathew Protheroe converted.
Gowerton continued to press, with flankers Tom Bebb and Shane Harris both prominent in the contact area, while debutant scrum-half Lewis Macdermott impressed with his tenacity around the fringes and full-back Will Bromham posed a threat with ball in hand.
Amman Valley's defence, with No. 8 Steffan Rees and centre Ceri Morris prominent, proved impossible to breach and they grew in confidence.
In the 34th minute, No. 9 Aled James powered over from short range for a try fly-half Ceri Rees converted, which levelled the scores.
Gowerton were back in front with the last kick of the half when Protheroe kicked a penalty from 20 metres.
In the 49th minute the visitors took the lead when James crossed for his second try. Rees converted, and although Gowerton pressed for a winning score, Amman Valley held on for victory.