Anxious wait over injured Wigan Athletic star
The young midfielder was having another fine game against top-of-the-table Lincoln when he pulled up lame just before the break.
He soldiered on to the interval, but didn't reappear for the second period - and will now be scanned to assess the extent of the injury.
"It's another tough one for us, another whack around the head," acknowledged Richardson.
"It's the demand of the fixtures, as well as the incredible demand on the players with the schedule.
"So much has been put on the shoulders of young lads such as Chris, who are playing at a level that they're just not used to.
"I felt he was excellent in the first half, he was winning every ball, covering every blade of grass, and he just felt the effects of that before half-time.
"He felt his hamstring, and it's a tough decision because obviously the kid wants to stay on.
"The easiest thing would have been to chance our arm and keep him on, but we're obviously not blessed with great numbers.
"As always we have to err on the side of caution, and he'll be getting assessed for that."
Merrie was replaced by Gavin Massey, who was making his first appearance in almost three months after a calf problem.
The experienced winger showed some nice touches during his run-out, and Richardson is hoping he'll have a big part to play in the run-in.
"Obviously Gav's been frustrated, he's been out for such a long period of time with different injuries," the Latics boss added.
"He's been part of this whole situation that I think, mentally and emotionally, he's had to get his head round things, as well as physically.
"But he's back on the pitch now, and if he can stay out there and stay fit, it'll be a big boost for us."