Mark McCall's men were eliminated from Europe last Saturday as they lost 25-16 to Toulon in the Challenge Cup semi-final.
McCall and Owen Farrell have already spoken this week about quickly switching their full focus to Gallagher Premiership matters with a home play-off semi-final within reach.
And Boyd, whose Saints side sit fourth, two places below Saracens, said: "We would expect a backlash from there because they were clearly disappointed with their performance against Toulon. Their management and players spoke out.
"We're not under any misapprehension here. We're pretty certain we're going down to take on a full-strength side.
"They'll have their injuries, as any side does, but I'm sure they will field as strong a side as they can.
"Their motivation, as is well documented, is that they want to secure a home semi-final."
Saturday's games are set to have a huge impact in the race for a top-four spot as Gloucester, who are a point below Saints in the standings, go to Harlequins.
That game, which takes place at Twickenham, will kick off two and a half hours before Saints start their match at Saracens.
And when asked whether Saints will be keeping an eye on it, Boyd said: "I'm sure Maurice (Hartery), our team manager, will have his earpiece in and will be listening and watching so we'll get some updates.
"We won't bother the players with that obviously because hopefully they will be focusing hard on what they need to do at Saracens.
"But it does have some implications both for Saracens and us.
"If Harlequins don't win then Saracens have probably already secured a home semi so their motivation might be slightly different.
"If Harlequins could do us a favour and deny some points to Gloucester, it might have an impact on what we need to do.
"But at the end of the day, we're just pleased that in the past five games that we've been playing knockout rugby, we're in control of our own destiny and hopefully the fruit will grow."