Winger Ewan Miller and replacement hooker Ali Ross led the way with two tries each as Watsonians put Biggar to the sword 74-5 at Myreside.
The game was well won at half-time, the ruthless hosts having built up a 43-5 lead.
The other tries for the leaders came from Neil Irvine-Hess, Mark Rennie, Jack Ferguson, Ramsay Young, Rory Steele, Tom Hart and Ally Ledingham.
Captain Ben Di Rollo kicked 17 points and Mike Ker two. Andrew Goodall got Biggar’s try.
Gareth Riddell scored two tries for Kelso as the Borderers’ good start continued with a bonus-point 37-5 win over Hillhead/Jordanhill at Poynder Park. Stuart Lowrie and Richard Minto also crossed for tries for the home side with Corey Venus on form with the boot and kicking 17 points. Blair McPherson got Hills’ only try, the Glasgow side still after their first win of the campaign.
Boroughmuir are in third after an impressive 37-17 home win over Dundee HSFP at Meggetland. The hosts led just 13-12 at the break, but stepped things up after the interval to get the bonus-point win.
Boroughmuir’s tries came through Malcolm Clapperton, Jordan Edmunds, Thomas Docherty and Craig Marshall, while David Reekie kicked three penalties and four conversions.
Callum Bowie grabbed a try for the Taysiders and Bryce Hosie kicked four penalties, but it was not enough as they slipped to their first defeat under Colin Robertson.
Peebles built on last week’s win over GHA with a convincing 32-0 victory over Stewart’s Melville, who have now lost two in a row.
Donald Anderson, Conor Blyth, Warren Kearney and Callum Scott scored the tries for Peter Wright’s men, while Greg Raeburn kicked 12 points.
The victory puts the Gytes side fifth, but the other promoted club, GHA, are still searching for their first win in the division. The Braidholm men have now lost three from three after Selkirk hammered them 45-10 at home.
Former Scotland Sevens man Fraser Harkness scored two tries for the visitors with Lee Kibble, Mike Davies and Darren Clapperton also crossing and Josh Welsh kicking the rest of the points.
Grant MacDonald scored GHA’s try with Murray Houston kicking five points, but they are in second bottom spot.