A solo try from Jonathan Joseph and nine points from the boot of George Ford gave Bath a 14-3 Premiership victory over Exeter Chiefs.
Bath signalled their Premiership intentions with a gutsy display, maintaining their discipline better than Harlequins, who saw Charlie Walker sent to the sin-bin for a tip tackle at the end of the first half.
George Ford's boot helped them to a half time lead, followed by a Jonathan Joseph try lighting up a game which failed to live up to expectations.
The win lifts Mike Ford's men six points clear of Quins, who ended a run of four wins in a row at the Rec.
Bath made their intentions clear from the off, going through the phases to force a penalty in under a minute. Ford nailed the early chance, and then increased his side's lead a few minutes later as Quins struggled to break out of their own half in the opening exchanges.
In a fierce, aggressive game Ford kept his composure when given the early chances. Bath found themselves with a nine point lead midway through the first half, their Premiership credentials starting to look more convincing as they continued to match up to the visitors.
The home crowd were incensed with referee Martin Fox, who awarded Harlequins their first chance to get on the board just before the half hour mark. Nick Evans was on hand to knock over a simple penalty, with clear cut chances still few and far between.
A frustrating half for both sides then boiled over when Walker was sent to the bin for a dangerous tackle. Walker's actions summed up a half which failed to live up to its billing.
Joseph then had the Rec bouncing with flash of quality which finally gave the supporters something to cheer, charging through the Quins line to finally deliver a try which a baying crowd had been waiting for.
Bath's lead could have been greater had it not been for Ford's inaccuracy. Despite managing the game with the ball in hand well, the England hopeful missed four kicks in a row to keep the opposition in the game.
Quins' held up charge over the line was as close as they came, as they were unable to muster up enough attacking phases to put pressure on Bath, whose superb home form continues.
Pens: Ford 3
Yellow Card: Walker
Bath: 15 Anthony Watson, 14 Horacio Agulla, 13 Jonathan Joseph, 12 Kyle Eastmond, 11 Matt Banahan, 10, George Ford, 9 Peter Stringer, 8 Carl Fearns, 7 Francois Louw, 6 Matt Garvey, 5 Dave Attwood, 4 Stuart Hooper (c), 3 Anthony Perenise, 2 Rob Webber, 1 Paul James
Replacements: 16 Eusebio Guinazu, 17 Nathan Catt, 18 Juan Pablo Orlandi, 19. Dominic Day, 20 Leroy Houston, 21 Martin Roberts, 22 Tom Heathcote, 23 Ollie Devoto
Harlequins: 15 Mike Brown, 14 Charlie Walker, 13 Matt Hopper, 12 Tim Molenaar, 11 Sam Smith, 10 Nick Evans, 9 Karl Dickson, 8 Nick Easter, 7 Chris Robshaw (c), 6 Luke Wallace, 5 George Robson, 4 Charlie Matthews, 3 Paul Doran Jones, 2 Dave Ward, 1 Joe Marler
Replacements: 16 Max Crumpton, 17 Mark Lambert, 18 Kyle Sinckler, 19 Nick Kennedy, 20 Tom Guest, 21 Sam Stuart, 22 Ben Botica, 23 Ollie Lindsay-Hague
Referee: Martin Fox