Saracens boosted their chances of securing a home semi-final with a commanding 27-12 victory over Harlequins in their Aviva Premiership clash at Allianz Park on Sunday.
Hooker Schalk Brits and flanker Will Fraser scored the tries with England fly-half Owen Farrell kicking their other 17 points. Fly-half Nick Evans kept Harlequins in contention into the second half with four penalties from five attempts but the reigning Premiership champions were second-best as they strove in vain to repel the Sarries' attack - or breach their rock-solid defence.
Saracens went into the match one point ahead of Leicester, who had moved into second with their win over Exeter 24 hours earlier, and four clear of third-placed Quins. Both sides wheeled out their big guns with players back from Six Nations duty. England's Farrell, Alex Goode, Chris Ashton, Brad Barritt and Mako Vunipola returned for Sarries, along with Scotland captain Kelly Brown. Harlequins had Mike Brown, Danny Care, Joe Marler and captain Chris Robshaw back in their starting line-up.
Saracens took the early initiative with Vunipola almost powering his way through before three players hauled him down just short of the line. The early pressure produced a third-minute penalty for Farrell, cancelled out three minutes later by Evans.
The New Zealander kicked Quins into a 6-3 lead after former England prop Matt Stevens was caught offside but Farrell levelled the scores after ex-England number eight Nick Easter went through on scrum-half Richard Wigglesworth at a ruck.
An excellent break by Ashton split the visiting defence and released flanker Fraser, who was denied a try by Brown's cover tackle. The combined efforts of the Quins defence prevented Fraser from recycling the ball at the cost of a yellow card for Marler.
Sarries capitalised by scoring 11 points while the prop was in the sin bin. Farrell landed the resulting penalty before kicking his fourth in the 23rd minute. A slick five-man handling move opened up the depleted Quins defence before Brits forced his way over for the game's first try but Farrell missed the conversion.
Marler returned as the visitors were awarded a 30th-minute penalty, kicked by Evans after Sarries No.8 Ernst Joubert offended at the breakdown. But the New Zealander then missed a penalty opportunity to reduce the deficit before Farrell was off-target on the stroke of half-time.
Saracens withdrew their former Harlequins winger David Strettle, who had suffered a leg injury late in the first half, at the interval, replacing him with United States international Chris Wyles.
Five minutes into the second half Evans made amends for his earlier miss to cut the gap to five points after the back-pedalling Saracens scrum was penalised.
Saracens responded with Brown, Goode and Ashton combining to put Harlequins in trouble again. Playing the advantage after Quins failed to release Ashton, Farrell produced a superb cross-kick into the arms of the unchallenged Fraser who touched down. Farrell converted to give Saracens a 24-12 lead. Farrell missed a 58th-minute penalty shot but made no mistake 10 minutes later to stretch his side's lead to 15 points.
In the closing stages, Ashton looked fortunate to escape with only a yellow card for a high tackle on Harlequins' replacement flanker Maurie Fa'asavalu after referee Greg Garner asked the television match official to review the incident. Harlequins tried desperately to make their one-man advantage pay but Saracens kept them out.
Saracens boss Mark McCall was quick to praise the influence of his returning internationals. "I've got to take my hat off to our English guys who had a difficult weekend last weekend. All of them, to a man, wanted to play today," said McCall. "It says a lot about the the environment and the general group that they are so keen to come back and enjoy it so much - but some of our non-internationals were pretty good today as well."
On Ashton's latest sin-binning - his fourth yellow card of the season, he said: "Chris had a really top game and got himself involved, for a guy who has taken his criticism over the last few weeks. Two years ago we thought Chris Ashton was the best player in the world and he just needs to have the confidence that his coaches believe in him. He mis-timed the challenge. There was no intent to cause any harm, It was just one of those things."
McCall was also impressed by the way man-of-the-match Vunipola took on opposite number James Johnston, who is joining Saracens from Quins in the summer. "The best thing he did today was scrummage against James Johnston. For a young prop, with only 12 months in the Premiership behind him, we all know he can do incredibly special things in the loose but he knows what he does in the tight is very important and he did it well today," McCall said. "We all know, from watching his performance today, how far he can go - and will go."
Conor O'Shea, the Harlequins director of rugby, admitted his side had under-performed. "We made too many errors and turned the ball over without really building any phases," he said. "Physically we were beaten, which is irritating beyond belief. We always pride ourselves on saying results don't matter but performances do - and we didn't perform today.
"We'll learn our lesson but the championship isn't decided today. They were worthy winners but we didn't perform anywhere close to what we know we are capable of. What we have to make sure is we play the way we can. We didn't today and you credit that to Saracens - they were excellent - but we will see them again."