Wigan Athletic v Sheffield Wednesday: Early team news
The big centre-back - who's been one of the key reasons behind the flying start - left the field against Cheltenham on the hour mark.
He'd reported the problem in the first half but was hoping to play through it.
"Jack felt a tightness in his hamstring in the first half," revealed boss Richardson.
"It's hopefully more precaution than anything, and fingers crossed he'll be okay.
"Obviously he'd be a big miss, but I think anybody would be a huge miss at the moment, given how everyone is playing.
"The lads who are starting at the moment have the privilege of the shirt, but everyone in the squad is worthy of being here and wouldn't look out of place."
If Whatmough doesn't make it, Curtis Tilt - who replaced him at the weekend - is standing by to make the first league start of his third loan spell from Rotherham.
Latics are aiming to consolidate top spot against the Owls, who were relegated from the Championship last season.
Richardson's side are aiming for a sixth win on the bounce, but he says no-one at the DW is losing their focus on what's in front of them.
"No-one's getting carried away, we've all been here too long," he said.
"All our challenges are ahead of us, and this is a very difficult week with Sheffield Wednesday to come in midweek and a trip to Gillingham on Saturday.
"The lads have been straight back to training, and the focus is really the players who haven't been involved.
"As we saw with Curtis Tilt on Saturday, he participated very well in the cup game last Tuesday, which meant he was ready to step in when required against Cheltenham."
He also has great respect for Wednesday, and their boss Darren Moore.
"You'd always expect Sheffield Wednesday to be up at the top of the league," Richardson added.
"They've got an abundance of fantastic players, a fantastic management team, and the size of the club obviously speaks for itself.
"Tuesday night under the lights at the DW, it'll be a massive occasion and I'm sure the game will be a great spectacle as well."
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