Fresh from SheBelieves Cup glory with England, Parris completed a devastating first-half hat-trick with three clinical finishes inside the box.
The hosts had initially taken the lead early on thanks to a strike from Brooke Chaplen, before Parris replied within ten minutes after being sent through over the top by Jill Scott.
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The striker then added two more strikes with half-time approaching, taking a touch and smashing in her second after good work by Demi Stokes down the left, before getting on the end of a Scott through-ball to claim the match ball within 40 minutes.
An end-to-end opening eventually saw the hosts sneak in front after just four minutes when Chaplen stole in ahead of Steph Houghton to an aerial ball before finishing beyond Ellie Roebuck when in on goal.
But we were undeterred by the early setback, replying within ten minutes when Parris made no mistake when sent through with a delightfully weighted pass over the top from Scott.
Both sides had chances to take the lead, Grace Moloney denying an angled Houghton free-kick after 20 minutes, and Remi Allen squandering a close-range chance after some penalty box pinball, but a devastating five-minute spell after the half-hour mark put us in control.
With ten minutes of the first half to go, Stokes took her time to cut back a left-wing cross for Parris, who made the most of limited space in the box to poke City ahead.
And three minutes later the forward was at it again, claiming the match-ball and a two goal lead for the Blues when she clipped in a delicate finish after once again ruthlessly combining with Scott in front of the Reading back four.
Stokes was in on the act early in the second-half, racing into space down the left before a quick one-two with Parris allowed the full-back to add her name to the scoresheet.
But it wasn’t all plain sailing for the Blues, as Fara Williams reduced the deficit from the spot after Allen had been brought down in the box just after the hour mark.
The hosts made it a nervy final few minutes when Kirsty Pearce reacted quickest to a smart Roebuck save following a looping cross into the box, but we dug in, withstood the late pressure, and held on to extend our lead at the top of the Women’s Super League to five points.
How we lined up
Roebuck started in goal, screened by a back four of Stokes, Jen Beattie, Houghton and Abbie McManus.
Keira Walsh and Scott sat in front, with Tessa Wullaert and Melissa Lawley on the flanks and Georgia Stanway in the hole providing support for Parris up front.
A quick turnaround sees the Blues back in cup action on Sunday afternoon, when we face Liverpool in the Women’s FA Cup Quarter Final at the Academy Stadium.