Aberdeen Grammar were comprehensively beaten 50-17 by Biggar as their recent solid home form ended abruptly.
The home side was outscored by seven tries to three after only trailing Biggar 17-7 at the break.
Aberdeen Grammar co-head coach Greig Ryan made no excuses following a tough afternoon for his side.
He said: “It was a bad day for us, but the guys played for 80 minutes and our replacements made a strong impact.
“It’s a tough league and this is a steep learning curve for us, but we need to learn from our mistakes to be competitive because we looked off the pace.”
Euan Bogle kicked Biggar into a 3-0 lead before Callum Dunlop and Ross Jackson tries dealt Grammar a significant blow early on.
The hosts grew into the game after this initial rough patch though, enjoying plenty of possession for the rest of the first-half as Sam Knudson kicked well from hand.
This was eventually awarded with a try as a superb Craig Shepherd break set up centre Steven Rutledge to score.
Tom Aplin added the extras on the stroke of half-time to bring Grammar back to within 10 points.
Visitors pulled clear in second half
However, it was Biggar who started stronger after the restart, extending their lead when Fergus Watson scored.
Several unforced errors continued to plague Grammar’s game, especially at the lineout, but they did hit back six minutes later when Aaron Robertson scored from close range.
The second rower’s try followed a probing run by Rutledge, which led to a highly effective maul by the hosts.
Aplin missed the conversion and with the score at 24-12 Biggar took control in the last 25 minutes.
The visitors added four more tries through Fergus Watson, Andrew Lamb, Ross Jackson and Andrew Orr.
A late consolation try did soften the blow slightly for Grammar as Euan Sinclair crossed for the hosts.
The hosts spread the ball from one wing to the other after a break by Ben Renton helped set the replacement up for their third try.
This defeat means Grammar remain seven points adrift of safety in National 1 as they host league leaders Kelso next week, before a difficult trip to Highland.
Highland fight back to secure win at Watsonians
Highland kept their slim title hopes alive with a battling 21-12 win in Edinburgh after they recovered from an early deficit of 12 points against Watsonians at Myreside.
Head coach Davie Carson was thrilled by the performance which led to a rare win on the road for his side.
He said: “Once we put a dreadful start behind us in which we conceded two tries, we were much the better side, demonstrating good focus and application.
“The win keeps us in fifth place. We have guys coming back from injury and work commitments, all keen to play at Ayr next week to start the second half of the season.
“While we may not catch leaders Kelso our eye is still on a high finish in this very competitive league.
“I thought prop Jonny Milton was outstanding today, his efforts typified the team performance.”
Highland punished for poor start in the capital
The Canal Park side were nowhere to be seen in the opening 15 minutes, giving away two tries, one of which was converted to trail 12-0 and on course for another on-the-road disaster, only to rally on the first class Myreside turf.
A well-worked try, touched down by full-back Rhuaridh McDonald and converted by stand-off Scott Fraser eased the northerners back into the game and although they trailed 12-7 at the break, the promise of better things to come was there.
So it proved, as Highland took total control, resulting in two more tries, dotted down by captain Callum Carson and lock Owen McDonald, both converted by Fraser.
Elsewhere leaders Kelso were narrow 22-21 winners at Ayr.
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