Sale lose Ford to injury in Saracens defeat while Northampton win
Ford had kicked Sale into an early lead but was forced off just seven minutes in after attempting a long-range penalty.
The news is an injury scare for England coach Steve Borthwick just over a month away from his side's first Autumn international against New Zealand.
"George just felt his quad when he went for that long-distance kick," said Sale physio Navdeep Sandhu.
"He thought like he felt he could carry on, but it was just slightly aware of it and I suspected that that meant it would get worse and worse and worse as the game carried on. So we decided to make the change."
Sale had led 13-12 at half-time after Gus Warr crossed for the only try of the first half.
However, Saracens came storming back with two tries from Elliot Daly plus fine finishes from Tobias Elliott and Jamie George to maintain their perfect start to the new season with two bonus point victories.
Lozowski has taken over kicking duties for Sarries in place of Owen Farrell, who joined French giants Racing 92 in the summer, and he slotted over 22 points from the tee in a superb display.
"It was a proper contest for 50 minutes or so and we were a little bit disappointed with just overall how we were in the first half," said Saracens boss Mark McCall.
"Our energy was not quite at the levels that we would want it to be at, but we thought that improved significantly in the second half and we were able to build a lot of pressure in the second against a good team."
Defending champions Northampton got their first win of the season after withstanding Exeter's late rally for a 30-24 victory.
Saints appeared to be cruising at 30-10, until England winger Immanuel Feyi-Waboso dotted down two converted tries in eight minutes to set up a tense finale.
Alex Coles, Chunya Munga and Rory Hutchinson scored Northampton's tries, while Fin Smith added 15 points with the boot.
Leigh Halfpenny celebrated his first English Premiership try as Harlequins picked up a 28-14 bonus-point victory over Newcastle.
The former Wales and Lions Test star race over for Quins' third try inside the first 31 minutes as Newcastle fell to a 23rd consecutive Premiership defeat.
