Head coach Pat Howard said he was particularly disappointed with his side's attack in the defeat by Northampton and also the previous week's win at Worcester Warriors, and will be looking for fresh impetus for the start of the final three months of the season.
"If you read just on the surface, with Leicester Tigers, playing at home, at one end of the table and Northampton at the other end, we should have played so much better," Howard said. "It should not have been a case of this penalty going over or a tough call from the ref on a drive. It just was not good enough. We have got to be far more consistent than that."
Howard selects his team to face Quins with Martin Castrogiovanni, Lewis Moody and Henry Tuilagi sidelined by injury, while also having to manage the international players who have been involved in the Six Nations over the last month.
"The three guys out at the moment are key players and in places we do not have a lot of flexibility," he said. "The three injured players are all forwards, for instance. But in the backs we have some good players who are not making the team."
Saturday's game features the return of Dean Richards to the club he served for 23 years as player, captain and director of rugby.
Howard, who worked as a player-backs coach with Richards, said: "He did some great things here and should be welcomed back at the club any time he wants to be. I hope he gets a very positive reception.
"As a manager, he keeps everybody on the right track. We do not have the same personality, John Wells was different as well, but we worked together as a successful team."
Richards led Quins to promotion back to the Guinness Premiership from National One last season and Howard said: "It was impressive how they came back up. They just said they were going to be so far ahead of the competition and they were determined for a full year. This season they lost the first five or six games but they got some continuity, they are in good form, and Dean and the management team deserve a lot of credit.
"The Harlequins side are working very hard, they are kicking their goals, they dig games out and they are doing well. They have produced two new England guys this season so there are some good things happening there."
