The Irish outfit romped to a 43-3 success over Benetton Treviso on their return to PRO12 action last weekend, a result that moved them into the top four and within four points of current table-toppers Glasgow Warriors.
And Humphreys insists that the remaining games in this clutch of matches, which begins on Friday with a tough trip to in-form Edinburgh Rugby, could prove crucial if they are to secure a semi-final spot in May.
"We targeted this block of four matches to try to maintain our place in the top four when the business end of the season comes around," the fly-half told the Irish Times.
"Obviously the short-term focus is winning the matches that will allow us to achieve that goal, and that starts at Murrayfield on Friday.
"This places an emphasis on the depth of the squad, and players coming in have to step up.
"We've had a lot of injuries, and while no one would deny that those players are missed, you just have to get on with it - it offers a chance for someone else.
Humphreys is also wary of the inside knowledge possessed by Alan Solomons, the former Ulster coach now in charge at Edinburgh.
"Solly knows some of us pretty well, so they'll be prepared," he added.
"They don't play a lot of rugby in their own half, so we know if we kick it down there we'll get the ball back.
"But once they get into your half, they are very physical and direct with a big back three.
"They also don't concede many tries and last weekend's victory over the Ospreys underlines their good form."
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