Marland Yarde's late try proved to be the difference as Harlequins saw off Leicester Tigers 25-19 at The Stoop on Friday.
The scores were level at the break with Ben Botica and Oli Bryant trading three penalties each.
Botica added two more from the tee in the second period before the Midlands' outfit moved ahead following Harry Thacker's converted try.
Quins' stand-off then kicked his sixth three-pointer and Marland Yarde crossed the whitewash as the hosts took a seemingly unassailable 25-16 lead late on.
Replacement Freddie Burns did score a penalty to give Leicester hope but they couldn't force the win and had to be content with a losing bonus point.
Harlequins and the Tigers both went into the match having lost their previous two games and the first half proved to be a tight and tense contest.
Richard Cockerill was forced into two late changes and that evidently affected the visitors' ability to find their fluency.
However, they were typically resilient and, when the penalty opportunities presented themselves, debutant Bryant was accurate from the tee.
The fly-half gave Cockerill's men the lead before Botica levelled matters. The respective stand-offs then traded three-pointers as the sides went into the interval level at 9-9 in what was a scrappy 40 minutes.
Errors continued to interrupt the play in the second period but it was a far more entertaining half and successive penalties by the Quins' pivot opened up a six-point buffer.
It appeared as though the hosts were on top but in Manu Tuilagi, a player who was making his return from a niggling hamstring injury, the away team had a potential game-changer. And so it proved when Tuilagi broke through the middle.
That burst gave the Tigers quick ball in the opposition 22 and Thacker took advantage when he touched down. Burns converted and Leicester led but it didn't last for long as Botica regained Quins' lead with a three-pointer before the number ten chipped through for Yarde to score the home side's only try.
That effort was the decisive moment in the match as, although Burns kicked a penalty to reduce the deficit, the Tigers had to settle for a bonus point.
Pens: Botica 6
Pens: Bryant 3, Burns
Harlequins: 15 Ross Chisholm, 14 Marland Yarde, 13 Winston Stanley, 12 Harry Sloan, 11 Tim Visser, 10 Ben Botica, 9 Tito Tebaldi, 8 Nick Easter, 7 Luke Wallace, 6 Mat Luamanu, 5 Charlie Matthews, 4 James Horwill (c), 3 Adam Jones, 2 Dave Ward, 1 Mark Lambert
Replacements: 16 Rob Buchanan, 17 Owen Evans, 18 Kyle Sinckler, 19 George Merrick, 20 James Chisholm, 21 Sam Egerton, 22 Tim Swiel, 23 Matt Hopper
Leicester: 15 Mathew Tait, 14 Peter Betham, 13 Matt Smith, 12 Manu Tuilagi, 11 Telusa Veainu, 10 Freddie Burns, 9 Sam Harrison, 8 Laurence Pearce, 7 Brendon O'Connor, 6 Tom Croft, 5 Mike Fitzgerald, 4 Ed Slater (c), 3 Fraser Balmain, 2 Leonardo Ghiraldini, 1 Marcos Ayerza
Replacements: 16 Harry Thacker, 17 Riccardo Brugnara, 18 Logovi'i Mulipola, 19 Graham Kitchener, 20 Jordan Crane, 21 Jono Kitto, 22 Oli Bryant, 23 Jean de Villiers
Referee: JP Doyle
Assistant Referees: Roy Maybank, Wayne Falla
TMO: Sean Davey