Reading have the worst defensive record in the league this season and Birmingham will be hoping to capitalise.
The Royals have conceded a shocking 62 times in 32 league matches.
Lee Bowyer's side have also been in improved form recently having drawn away at Stoke and beaten Luton.
Hernandez has already netted three times for Birmingham since arriving in January.
The striker has made a strong start to life at the Midlands club.
He is once again expected to start in attack with Lyle Taylor on Tuesday.
Match preview: Reading vs Birmingham City
Reading remain strongly threatened by relegation this season with the Royals now sitting in 21st.
Just five points separates them from the bottom three with Derby County now in pursuit of them.
On Tuesday, they will have a new man in the dugout with Veljko Paunović being sacked and Paul Ince replacing him as interim.
Paunović was sacked despite his side managing to secure a shock win on the weekend as they defeated Preston 3-2.
They have now gone two games without a defeat having ended a run of seven straight defeats.
Birmingham move clear of bottom three
Birmingham have now opened a 16 point gap between themselves and the bottom three.
The Blues have lost just twice in their last seven matches.
Lee Bowyer's side managed to defeat Luton Town before holding Stoke to a 2-2 draw away from home.
The Midlands club produced an impressive performance at Stoke to earn a valuable point on Saturday.
Reading team news
Paul Ince will be several key players on Tuesday including Alen Haliovic, Scott Dann, Ovie Ejaria and Josh Laurent.
Femi Azeez, Dejan Tetek and Felipe Araruna are all also ruled out of the match.
Birmingham City team news
Troy Deeney remains sidelined for the Blues with an injury.
The defensive duo of Teden Mengi and Marc Roberts will also be missing.
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