Evans was United's only fit central defender heading into the game and failed to reappear for the second half as Dimitar Berbatov bagged a hat-trick.
And Ferguson confirmed the Northern Ireland defender will not make the New Year's Eve encounter with Blackburn.
"Jonny came off injured. He has a calf injury and will be out for two weeks," Ferguson told BBC Radio Five Live.
"We have had a nightmare the last few days. Phil Jones and Chris Smalling have both been ill. Rio Ferdinand called off yesterday with a back injury and Jonny Evans has come off at half-time.
"It does put you under pressure."
Ferguson is hoping Jones and Smalling will have recovered from their problems before the Blackburn game, although with a trip to Newcastle to follow and then the blockbuster FA Cup third round tie with Manchester City at the Etihad Stadium on January 8, it is the wrong time to be affected by an area of the pitch from which skipper Nemanja Vidic will be missing for the rest of the season.
It is the one cloud on a very healthy festive period for United so far.
The Red Devils' second successive five-goal win allowed them to move level on points with neighbours Manchester City, and slice the Blues' goal difference advantage in half.
However, the game turned on Connor Sammon's red card when United were just a goal ahead towards the end of the first half.
Sammon stuck out his arm to try and shield possession, caught Michael Carrick in the face and Phil Dowd promptly sent him off.
"The red card is a shocking decision," said Martinez.
"There was a little bit of a fight, as there was every time the two players went for the ball. None of them should have been a red card. None of them were malicious. There was no intent.
"If you want to show a red card using those standards, do it, then you will end up with six men each.
"Anyone who has been on a football pitch knows that incident was a normal action.
"I was surprised when he gave the free-kick. To see the red card, I was gobsmacked."
Even Ferguson admitted it was "harsh".
However, his side took full advantage.
Park Ji-sung had already put the hosts in front and within two minutes of Sammon's exit, Berbatov added another, by using tactics Martinez felt were similar to that his own side were punished for.
United cut loose after the interval, with Berbatov adding another followed by an effort from former Wigan man Antonio Valencia.
Making only his second Premier League start of the season, Berbatov wrapped things up with a penalty after Wayne Rooney had stood aside following Antolin Alcaraz's foul on Park, which seemed to take place outside the box.
"It was the right game for Dimitar," said Ferguson.
"I needed his height in terms of set-piece play against us and he weighed in with a hat-trick.
"We are really pleased for him. It helps his confidence. He has not had the best start to the season in terms of selection because of the options I have, with (Danny) Welbeck, Rooney and (Javier) Hernandez."
Ferguson will receive the perfect 70th birthday present of a place on top of the Premier League if his side beat Blackburn at Old Trafford on New Year's Eve, 24 hours before Manchester City visit Sunderland.
However, Martinez feels Roberto Mancini's men face a far more considerable test of their mettle over the next few months.
"What Manchester United have is that mentality," said the Wigan chief.
"They adapt to adversity. You can see everyone taking responsibility and using that to get a result.
"That is the biggest strength they have had for 25 years.
"That is why any team that wants to win the league, beyond any sort of money, or any sort of players you want to bring in, need to beat Manchester United mentally.
"That is the biggest battle."