Sean Dyche must find the right formula as his Watford side look for their first home win of the season.
Having followed up back-to-back early-season defeats with a four-match unbeaten run in the Championship - which included the club's only victory to date away to Reading - the Hornets fell back into bad habits as they were beaten 1-0 at home by Nottingham Forest on Saturday.
Manager Dyche made one change against the Reds after seeing striker Andreas Weimann recalled from his loan spell by Aston Villa, Joe Garner coming into attack against his former employers.
It was Dyche's first switch to his starting XI in four games and, with no new injury or suspension concerns, he must now decide whether to go again with the same line-up or call upon the likes of Chris Iwelumo or Troy Deeney from the off.
Watford have so far lost three and drawn one of their four home matches this season and are one of five clubs in the second tier still to taste success on home soil.
Goal-shy Millwall are set to be without strikers Darius Henderson and Josh McQuoid.
Henderson has been sidelined with a calf injury and McQuoid missed Saturday's 3-0 defeat at Derby with a virus, and neither are expected back in time to figure at Vicarage Road.
Jay Simpson and Dany N'Guessan started in attack at Pride Park with John Marquis, who needs a hernia op, coming off the bench.
But they could not find the net and their goal drought now stretches back five league games.
Midfielders Therry Racon (ankle) and Tamika Mkandawire (groin) are still out along with forward Shaun Batt (calf).
Hamer Bouazza and Darren Ward will come up against their former club while Lions manager Kenny Jackett faces the side he played for, coached and managed.