Saracens returned to the top of the Guinness Premiership with their sixth consecutive victory, 21-15 over Leeds.
Fiji centre Kameli Ratuvou scored tries either side of half-time in a scrappy game punctuated by 27 penalties.
Leeds replied with four penalties and a drop-goal from fly-half Ceiron Thomas, but rarely threatened the Saracens line.
Saracens had Leeds on the back foot from the kick-off, twice forcing desperate defence by the visitors close to their line and they had an early let-off when Glen Jackson screwed a fourth-minute penalty wide following a scrum offence.
Jackson made amends inside two minutes, chipping home his second penalty from 25 yards after Leeds were adjudged offside, but little technical errors suggested the hosts were not into their stride as Leeds snapped at heels and harried ball-carriers into mistakes.
So it was no surprise when referee David Rose penalised Saracens in the 17th minute for taking down a scrum. Thomas equalised with a fine kick from wide out on the left.
Within three minutes, Saracens targeted wing Lee Blackett for the second time and he again blundered, presenting Jackson with the opportunity to restore his team's three-point lead, only for Thomas to level matters again with a goal in the 25th minute.
Saracens scrum-half Justin Marshall made way for Neil de Kock in the 27th minute, limping out of the action on his left leg.
Thomas was sin-binned in the 33rd minute after deliberately handling in a ruck to deny Saracens a try-scoring opportunity. When play switched across the line - Jackson arrowing out a fine long pass - Noah Cato looked like scoring in the right-hand corner but Seru Rabeni's excellent tackle forced a knock-on.
At this stage it was difficult to believe that Saracens were seeking to preserve a 100% Guinness Premiership record and return to the top of the table.
They finally broke the deadlock on the stroke of half-time. Leeds full-back Leigh Hinton scorned the chances to kick possession dead with time over and cost his team a try.
Schalk Brits broke through the middle, and when Jackson passed left to Ratuvou he dummied to pass on to Chris Wyles before smashing through Richard Welding's tackle to score. Jackson's conversion was wide.
Leeds reduced the deficit to two points when Thomas kicked his third successful penalty two minutes after the break only for Saracens to score their second try off a twice-taken penalty.
Referee Rose decided Leeds were not 10 yards back when Jackson made his first tap and go, and when Saracens won the resultant lineout, three passes armed Ratuvou to crash through the defence on the left of the posts, Jackson converting.
Another Thomas penalty kept Leeds in touch, but his first miss, on the hour, was a lost opportunity to reward a period of pressure on their hosts.
Before Will Greenwood started breaking down moves off the field, he was doing the business on it - and no match better illustrated the type of marauding centre he was than in a virtuoso performance against Wales.