Colchester United will host Brentford in the second round of the EFL Cup at the Colchester Community stadium on Tuesday.
Last season, Millwall came close to getting a playoff spot but eventually fell short in their quest. They finished ninth with 69 points from 46 games.
Reading will be taking on Colchester United on Saturday in a pre-season friendly with both teams looking to kickstart their preparations for 2022/23.