Johnson felt hard done by
Reading are taking precautions over the ankle injury suffered by Sean Morrison in the defeat by Southampton amid fears he will miss the crucial trip to Sunderland.
The defender sustained the problem shortly after the hour of Saturday's 1-0 loss and had to be substituted before later having to leave St Mary's on crutches.
Reading are yet to determine the full extent of the injury but boss Brian McDermott does not think Morrison will be available for Tuesday's game at fellow Premier League strugglers Sunderland.
And the 21-year-old can be added to a sidelined list of Jimmy Kebe, Pavel Pogrebnyak, Chris Gunter and Alex McCarthy, while Jem Karacan is only just back in light training.
McDermott told Reading's official website: "We've been unfortunate with injuries.
"I'm not one to really moan about it but we've had long-term ones with the likes of Alex McCarthy. But that's why you have a squad.
"I'm not sure Morro' will be available Tuesday, it's his ankle and he's on crutches as a precaution. Pavel is out, Jem, Jimmy and so on. Come Tuesday, we'll be ready again."
Goalkeeper McCarthy suffered his shoulder injury against Queens Park Rangers at the beginning of November and he is now facing an extended spell on the sidelines after undergoing surgery.
Johnson felt Dan Burn's second-half header crossed the line but referee Andrew Madley adjudged it did not.
The Londoner said: "I think there was a header where their goalkeeper saved it off the line. We will have to look at the video because we genuinely felt it was over.
"We knew they are an experienced side and have players who show a lot of passion, and we had to match that.
"It was a great game for a 0-0, and made for a good atmosphere. It felt like a Championship match.
"Like when Manchester United play Manchester City, it could have gone either way. They created some chances, as did we.
"I think their goalkeeper was probably man of the match for me. I was pleased with our performance and if we can continue to perform like that then we continue to get results.
"I felt our performance was good enough to win that game - and that was what I was most pleased at."