Reports suggest that Morrison will join on a one-year loan deal from Lazio, with Atlas retaining an option to buy after it ends.
The 24-year-old former Manchester United starlet will play a club currently fighting relegation and reeling from captain Rafa Marquez being sanctioned by the U.S. Treasury Department for an alleged connection to a drug trafficking organization.
Morrison was tipped to be a future star for United and England, but disciplinary problems off the field saw him move from Old Trafford to Birmingham, then West Ham, Cardiff and Lazio.
Morrison was linked with a loan move back to Birmingham City earlier in the transfer window, but a deal couldn't be worked out with Harry Redknapp's team.
Atlas are expected to sign Morrison player shortly, with multiple reports suggesting a deal is close to being concluded.