Reigning champions Exeter moved to the top of the Aviva Premiership despite the unconvincing manner of their 31-17 win over injury-hit Harlequins at Sandy Park.
Their bonus-point success moved them two points ahead of Saracens, who they meet at Allianz Park next Sunday.
Harlequins, inspired by the skill of young fly-half Marcus Smith, were the better side for large parts of the game but a number of marginal refereeing decisions went against them.
Jonny Hill scored two of Exeter's tries, with one each for Olly Woodburn and Lachie Turner, while Gareth Steenson converted all four and kicked a penalty.
Tim Visser and James Chisholm scored tries for Quins, with Smith adding two conversions and a penalty.
Exeter took the lead in the fifth minute with a splendid try from Turner. A poor kick from James Lang surrendered possession to the Chiefs before a jinking run from Phil Dollman saw him beat three defenders to send the wing over.
Quins were level when bursts from Mat Luamanu and Smith put the home defence of the back foot and Chisholm evaded Mitch Lees' tackle to run 25 metres to score.
Smith converted but missed a penalty so it remained at 7-7 at the end of an enterprising first quarter.
Quins had marginally the better of that opening period but it was Exeter who regained the lead when slick passing from their three-quarters created a well-worked try for Woodburn.
The visitors then suffered a further setback when Harry Sloan left the field with a leg injury and was replaced by Charlie Walker.
They soon overcame that blow to score their second try when Smith chipped ahead and outmuscled Steenson for the loose ball to send the supporting Visser over the line.
Moments before half-time, Quins looked to have scored a third try when a neat break from Smith sent James Horwill crashing over but the TMO ruled that the visitors' skipper had been held up by Woodburn.
However, Exeter were penalised and Smith kicked a penalty to give his side a 17-14 half-time lead.
Within four minutes of the restart, Exeter were back in front when Hill scored from close range after Don Armand softened up the defence with a couple of surges.
Quins appeared to have regained the lead when Lang collected Smith's chip ahead to score. But once again the rub of the green went against them when the TMO ruled Visser put a foot in touch earlier in the move.
Going into the final 15 minutes, the game was still in the balance with Exeter making a number of slipshod errors in an uncharacteristic performance from them.
The whole-hearted Woodburn was exempt from any criticism and his run started the move which resulted in Hill's second and Exeter's bonus-point try, before Steenson kicked a last-minute penalty.