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The visitors opened the scoring with their first attack of the match as Mike Ellery slipped down the sideline before leaping over in the corner for his third try of the season.
The home side had the majority of the possession in the first half, but had to settle for a couple of penalties from Billy Twelvetrees, keeping the scores close at the interval.
Owen Farrell took over the kicking duties in the second half for Saracens, with the England fly-half and Twelvetrees each making three penalties, keeping the visitors two points ahead with four minutes remaining.
Gloucester stole the ball from a Saracens lineout in the final minute as they pushed for a match-winning score, but the defending champions quickly forced the turnover before kicking the ball into touch.
The result keeps Saracens at the top of the table, while Gloucester sit second, having won in the opening round of fixtures.