Harlequins ran in four second-half tries as they claimed a 32-20 European Rugby Challenge Cup win at Cardiff Blues.
Before kick-off in the Pool 3 clash, a minute's applause was held for New Zealand legend Jonah Lomu after his passing on Wednesday at the age of 40.
Lomu enjoyed a short spell with the Blues from 2005 to 2006.
The host - missing Wales captain Sam Warburton due to illness - led 6-3 at the break after a first-half that was halted due to a head injury to Harlequins captain Jack Clifford.
Clifford, who was taken off on a stretcher, later posted on Twitter to allay concerns over his health.
Tries from Tim Visser, Ollie Lindsay-Hague and Charlie Walker gave Harlequins a 25-6 lead with 15 minutes to play.
After Cardiff's Matthew Rees was sent off seven minutes from time for a stamp on Nick Easter, Danny Care's late try ensured a bonus-point triumph as the home side's attempt at a comeback fell short.
In the day's other game, Harlequins' Premiership rival Gloucester won on the road by beating Pool 4 rival La Rochelle 33-20.
Four first-half penalties from Scotland international Greig Laidlaw helped Gloucester to a 19-13 half-time lead.
Jason Eaton's 43rd-minute score gave La Rochelle a one-point advantage, only for Steve McColl and Charlie Sharples to cross and seal victory for Gloucester.