Ugo Monye and George Robson scored two tries apiece as Harlequins thrashed London Welsh 40-3 at the Stoop.
The home side picked up where they left off last weekend over the road at Twickenham Stadium as they scored two tries in the opening ten minutes to set the tone for a comfortable victory over the Premiership new boys.
George Robson powered over for the first in the opening few minutes and when Ugo Monye crossed for his first try of the season after Nick Evans had opted to kick for the corner rather than take a shot at goal the writing was already on the wall.
Former Scotland fly-half Gordon Ross did get the visitors on the board with three points midway through the first half but Monye's second try made it 21-3 at the break and the gulf in class was plain for all to see.
London Welsh's cause was not helped at all in the second half by two yellow cards, one to Paulica Ion early on and another to Tom Arscott with five minutes remaining, and Quins could and perhaps should have scored more tries than the six they did manage.
The increasingly impressive Robson completed his own brace from short range just over ten minutes after the restart to confirm that the home side's bonus point was well and truly in the bag before George Lowe and new signing Ben Botica finished off the scoring in the final quarter.
Lowe touched down after a superb break and chip ahead from the excellent Mike Brown and Nick Evans kicked his fifth conversion of the evening before being replaced by the young Kiwi Botica.
And, with substitutions happening left, right and centre and Arscott in the sin bin, Botica went over for a debut try to cap off a resounding victory, giving Quins their second bonus-point win and showing Welsh that a tough season lies ahead.
Tries: Monye 2, Robson 2, Lowe, Botica
Cons: Evans 5
For London Welsh:
Harlequins: 15 Mike Brown, 14 Tom Williams, 13 George Lowe, 12 Jordan Turner-Hall, 11 UgoMonye, 10 Nick Evans, 9 Karl Dickson, 8 Tom Guest, 7 Chris Robshaw (c), 6 Maurie Fa'asavalu, 5 George Robson, 4 Olly Kohn, 3 James Johnston, 2 Joe Gray, 1 Joe Marler.
Replacements: 16 Rob Buchanan, 17 Darryl Marfo, 18 Kyle Sinckler, 19 Charlie Matthews, 20 Nick Easter, 21 Danny Care, 22 Ben Botica, 23 Matt Hopper.
London Welsh: 15 Tom Arscott, 14 Phil Mackenzie, 13 Sonny Parker, 12 Hudson Tonga'uiha, 11 Joe Ajuwa, 10 Gordon Ross, 9 Tyson Keats, 8 Ed Jackson, 7 Mike Denbee, 6 Daniel Browne, 5 Matt Corker, 4 Jonathan Mills (c), 3 Paulica Ion, 2 Neil Briggs, 1 Frank Montanella.
Replacements: 16 Dan George, 17 Tom Bristow, 18 Arthur Joly, 19 Kirill Kulemin, 20 Alfie To'oala, 21 Nick Runciman, 22 Seb Jewell, 23 Nick Scott
Referee: Luke Pearce