If the move for Engels is completed, it would look like a clear statement of intent. The midfielder is widely viewed as a player who can help in possession, carry the ball through pressure and give Celtic another option in games where control matters as much as tempo.
The timing matters too. Bringing in a player before the window shuts is one thing; bedding him into a side chasing trophies immediately is another.
The report says Johnston could miss a few weeks, and that would be an unwelcome interruption. He brings reliability on the right, energy in transition and a level of defensive aggression that helps Celtic pin opponents back.
Against Dundee United, the issue is not just who fills in, but how much the shape changes.
The other theme hanging over this tie is what comes next in the market. Reports suggest further arrivals are still possible before the window closes, which fits the sense that Celtic are not finished reshaping the squad.
That makes Saturday’s match worth watching beyond the result. It should offer clues about depth, priorities and whether Celtic still need one or two more pieces before the next big stretch of the season.