Kelly Chambers' side have needed penalty shoot-outs to overcome Leicester and Tottenham in the previous two rounds, but they come into the game on the back of a 4-0 defeat to Arsenal in the WSL last weekend.
Deanne Rose remains out for the Berkshire side, but apart from that it's a largely fully-fit squad for Kelly Chambers to choose from.
Lily Woodham came off the bench during last weekend's defeat to Arsenal, so she may be pushing for a start.
There is every chance that Hayes rotates her squad for the cup tie, but she hasn't given too much away pre-match.
Reading: Moloney; Bryson, Evans, Mayi Kith, Mukandi; Moore, Vanhaevermaet, Eikeland; Harries, Wellings, Rowe
Chelsea: Berger; Perisset, Buchanan, Bright, Carter; Leupolz, Ingle; James, Fleming, Charles; Kerr
Reading - Rachel Rowe
The Welsh forward was the match-winner during Reading's last victory against West Ham at the beginning of March.
She showed a few glimpses of real quality last weekend, despite the tough evening for her side.
If the Berkshire side are to cause a cup shock, you feel Rowe will need to be at her best against a stubborn Chelsea defence.
Chelsea - Sam Kerr
She's one of the best players in the world and the Australian proved her quality last Sunday, with a beautiful finish to earn her side all three points.
Kerr has struck four goals in the FA Cup so far this season, including a hat-trick during a 3-2 victory against Liverpool in round four.
She also found the net during the 2-0 win against Arsenal in the last round, and it seems like almost every time Kerr steps on a pitch, she produces something special.
Back in December, the sides met in the WSL. Jelena Cankovic scored twice and Kirby also found the net to put the London side 3-0 to the good. Sanne Troelsgaard and Amalie Eikeland responded to make it 3-2, but Chelsea held on.
The last time that Chelsea made the visit to Reading, a Deanne Rose goal earned a 1-0 victory for the Royals.
Where is the match being played?
The game is being played at Reading’s Select Car Leasing Stadium.
What time is kick off?
The match will kick-off at 2pm on Sunday 19th March.
How can I watch?
The game is available to watch for free on the FA Player.