Instonians coach Clem Boyd was relieved to get a late 22-21 derby win over Queen's at Shaw's Bridge to make it four wins out of four.
The home side needed a late Niall Malone try to seal victory and keep them joint top of the table with Bruff.
"I think we stole it at the end and fair play to Queen's they played the smarter rugby, but unfortunately they didn't have the scrum to back it up," said Boyd.
"That has been our toughest test and it's an excellent Queen's team. We targeted 18 points from the first four games and we have 19, but we need to tighten up and re-group for the next two games."
Queen's led 18-8 at the break with tries from hooker Paul Jackson and winger Chris Cochrane while Ian Porter kicked eight points with the home team replying through an Owen McMurray penalty and a Darren Lyttle try. Lyttle added his second try which was converted before Porter added another penalty for Queen's.
Malone pounced on a mistake in the students defence to dash under the post and the former Irish out-half converted his own try to seal victory.
Meanwhile, Banbridge moved up to third with a 26-17 bonus point victory against Naas at Rifle Park.
The home side led 15-0 at half time with Jeff Dodds, Gareth Martin and Stuart Wilson going over. Matthew Irvine's second half try sealed the bonus point.
Rainey have put a poor start behind them and recorded their second win, beating Old Wesley 26-8 at Donnybrook.
Two Michael Glancy penalties and a Josh McMurray drop goal give them a 9-3 interval lead.
A second half try from Evan Stewart and two from Damien Campbell saw the Old Boys home.
Ards' discipline deserted them in Cork allowing Sunday's Well to edge home 12-6 while City of Derry are rooted to the foot of the table with one bonus point from four games after they lost a third home game, going down 27-17 to Corinthians.