"That might be the debate to maybe have to tell Grigg and Walker that they're not in. That's the conundrum," Ratten said from Visy Park on Wednesday.
"I think our depth is a pleasing aspect and we've got Nick Stevens who will come in the following week and then Andrew Carrazzo will be fit the following week. It starts to get a lot more difficult.
"It's a good thing to have … but it's not a great task telling blokes that they're not in the team."
Brad Fisher also pushed his claims for selection with a solid hitout in a VFL trial game.
Ratten dispelled the widely-held belief that one or two of last week's debutants would be the most likely to make way.
"We had four new blokes and they all put themselves into the game physically which was great," he said of the first-up efforts of Mitch Robinson, Jeff Garlett, Aaron Joseph and Sam Jacobs.
"They were nearly the benchmark. That contest that Robinson had with Troy Simmonds early in the game really set the tone for the whole team … I thought it was a super effort."
The coach was unequivocal when asked if Robinson had done enough to hold his spot.
"He won't be out, I'll tell you that," he said.
The Blues will take on the Brisbane Lions at Docklands on Saturday night, with Ratten looking forward to pitting his young backline against the twin towers of Jonathan Brown and Darren Bradshaw.
The Lions duo presents a clear danger to Carlton's quest to maintain a winning start to the year, but Ratten felt the game would be won or lost further up the field.
"It will be about ball supply. If Josh Drummond is allowed to waltz out of half-back I think Bradshaw and Brown will get it on a platter and it wouldn't matter if you had Scarlett or these type of blokes down there," he said.
"We've got to put a bit of pressure on the way the ball comes out of our forward 50. That will be the key I think.
"They've got a really strong midfield [as well], they're really underrated, but they've got talent there.
"We'll have that challenge to make sure they don't get any dominance around the centre bounce. Especially at Docklands because you can score quickly there from centre bounces."
