Owen Farrell kicked all of Saracens' points as they kept the pressure on Premiership leaders Harlequins by beating London Irish.
The Exiles took the lead from Tom Homer's kick but that lasted only three minutes, with Farrell scoring three penalties to make it 9-3 at the break.
Daniel Bowden made it 9-6 with a penalty before Farrell kicked two more.
David Paice rescued a losing bonus point for Irish with the game's only try, but Bowden missed the conversion.
Second-placed Saracens lost wing Joe Maddock to a leg injury after three minutes, with David Strettle his replacement.
Two minutes later Homer fired Irish into the lead, but Farrell soon cancelled that out.
Homer squandered a chance to restore the Exiles' lead, missing a penalty after Saracens had hooker John Smit sin-binned for picking up the ball after it had emerged from the back of a ruck.
Farrell made him pay with two more kicks before the half-time break and Sarries could have scored a try on the stroke of half-time when the 20-year-old fly-half chipped the ball over for James Short to cross, but the video referee ruled the winger had failed to ground the ball under pressure from Bowden.
The Exiles went on the attack after the break and Bowden scored a 49th-minute penalty but three minutes later Farrell restored the six-point advantage and he then added a 40m effort to leave the Exiles facing a trip back to Berkshire with no points.
However, with four minutes left the pack propelled Paice over the tryline to secure a losing bonus point.
Saracens rugby director Mark McCall:
"A lot of players put in a big shift for Irish out there and we had to defend well at times.
"But we have a number of guys in the walking wounded at the moment and hope to have Brad Barritt and Charlie Hodgson back for the weekend, while Schalk Brits will have served his suspension."
London Irish head coach Toby Booth:
"They are the champions, well drilled and well coached. You must take points when you get as close to their line as we did on a number of occasions.
"The difference between the teams was taking chances. We left their 22 too often empty handed. Saracens kicked all of their goals and left us with only one point to show for our efforts.
"Tom Homer deserves a mention because he was very sick all week yet insisted he wanted to play. By half-time he was running on empty.
"And three of the four locks out there are internationals, yet the outstanding lock was Matt Garvey whose carrying and all-round contribution make him the typical modern second row."
Saracens: Goode; Maddock, Wyles, Powell, Short; Farrell, Spencer; Stevens, Smit, Nieto, Borthwick, Botha, Wray, Saull, Joubert.
Replacements: Strettle for Maddock (6), Gill for Nieto (49), Kruis for Botha (51), George for Smit (56), Brown for Wray (59), Taylor for Short (69). Not Used: Du Plessis, Baldwin.
Sin Bin: Smit (11).
London Irish: Homer; Ojo, Ansbro, Spratt, Thompstone; Bowden, Hodgson; Corbisiero, Buckland, Ion, Kennedy, Garvey, Danaher, Gibson, Hala'ufia.
Replacements: G Armitage for Homer (41), Allinson for Hodgson (51), Paice for Buckland (51), Evans for Kennedy (51), Rautenbach for Ion (53), Dermody for Corbisiero (53), Treviranus for Hala'ufia (70). Not Used: Jarvis.
Ref: Andrew Small (RFU).