Colchester United take on Millwall in the latest pre-season fixture.
It will be another step up for John McGreal and the squad, following games against non-league opposition.
The Lions returned from their training camp in Portugal, and beat Cambridge United 2-0 at the Abbey on Saturday.
He told the official website: "Millwall will no doubt be our toughest test, they are a decent Championship side that weren't that far off the Play-Offs last season and will want to challenge again this time round."
"We might well have less of the ball than our previous pre-season games but that will allow us to guage how well we are progressing defensively.
"It will also mean that we have to make good use of that possession if we aren't getting on the ball as much - can we still play the football we want to play and create the chances in this game that we did in the earlier matches.
"That's what we'll be asking from the players, along with making sure they continue to increase their fitness levels ahead of the new season in eleven days time."
You can still purchase your ticket and car park space online for this game, and for the fixture against Gillingham on Saturday.