Leeds Carnegie slipped to a 32-6 defeat to the second placed side in the Guinness Premiership but the scoreline did not reflect an even contest that the home side played their full part in.
Harlequins scored with the last play of the game to secure a bonus point after former Leeds star Danny Care had earlier scored on his first return to Headingley Carnegie.
Leeds showed some early promise but gave Quins the first scoring chance when Andy Tuilagi came in with a high challenge on Tani Fuga 38 metres out from his own line. Adrian Jarvis elected to kick at goal and gave his side a 3-0 lead after three minutes.
Former Leeds scrum half Danny Care showed an early glimpse of his skill when he broke through at the tail of a line out before chipping over the defence only to be beaten to the ball by Rob Vickerman, who touched down to get a 22 metre drop out.
However, Quins did get the first try after 13 minutes when quick thinking by Jarvis spotted space out wide, he kicked to the corner and full back Mike Brown was on hand to score in the corner. Jarvis missed the touchline conversion but his side now led 8-0.
Leeds managed to cut that deficit two minutes later when Alberto Di Bernardo kicked a penalty from 40 metres out after a knock on by the visitors could only be gathered by a man in an offside position.
The game failed to spark into life for the majority of the first half with neither team able to build momentum due to a number of knock ons caused by the slippery conditions. Leeds found themselves down to 14 men when Vili Ma'asi was sin binned for deliberately spoiling a Quins ruck however Jarvis missed the chance to extend his side's lead from the subsequent penalty.
However, with six minutes remaining in the half, the Quins fly half was on a target with an effort from 35 metres out to make it 11-3 to the visitors.
Leeds had to withstand a late surge by Quins at the end of the half as they enjoyed a prolonged spell of possession on the home line but the defence held firm and kept Quins at bay to go in 11-3 down at the break.
Leeds came out determined in the second half and took the game to Quins. Good work in the line out helped secure possession and eventually the pressure told as Quins were penalised ten metres from their line. Di Bernardo elected to go for goal and made the score 11-6 after 44 minutes.
After that early set back, the visitors finally settled into a rhythm and got the next score through Care. Leeds seemed to be harshly done to by referee Dean Richards, who allowed Care to take a quick tape after an offence at a scrum whilst both packs were still bound in the scrum. Jarvis added the conversion to make it 18-6 after 52 minutes.
Leeds could have hit straight back after a great break by Richard Welding but he was just tackled short of the line by Jordan Turner-Hall and the chance had gone.
Harlequins decided to revert to a close quarters battle as they looked to gain maximum points from the game. After several drives near the line, eventually replacement Jim Evans was bundled over for a try. Jarvis converted to give the scoreline a flattering look to the visitors at 25-8.
The crowd of 3,854 were brought to their feet with six minutes remaining when Leigh Hinton looked to have scored a well crafted try from a brilliantly floated pass by young Luther Burrell, however referee Dean Richards cut the celebrations short with yet another harsh call on the home side.
Two minutes into injury time, Quins added insult to injury by grabbing a bonus point try through captain Will Skinner. Jarvis added the conversion to make the final score 32-6 to the visitors.
Leeds Carnegie: Hinton, Welding, Vickerman, Tuilagi, T Rock, Di Bernardo, Bedford, MacDonald, Ma'asi, Hopcroft, Bouza, Hooper, Oakley, Fourie, Clark
Replacements: Pala'amo for Hopcroft (53), Rawlinson for Ma'asi (67), Lund for Bouza (53), Balding for Clark (53), Edwards for Bedford (67), Burrell for Tuilagi (58), Greendale for Welding (71)
Harlequins: Brown, Williams, Monye, Turner-Hall, Keogh, Jarvis, Care, Jones, Fuga, Ross, Kohn, Robson, Robshaw, Skinner, Guest
Replacements: Botha for Fuga (53), Brooks for Jones (69), Evans for Kohn (53), Easter for Guest (64), Gomarsall for Care (63), Strettle for Williams (53), Barry for Turner-Hall (70)
Referee: Dean Richards