LEE Gregory and Joe Martin are doubts for this weekend's League One fixture against Bradford at The Den.
Gregory has missed Millwall's last three games after going off with a hip problem in the 2-1 win over Sheffield United on August 20.
Defender Martin is struggling to recover from the shoulder injury that forced him off against Chesterfield last weekend.
With Shane Ferguson away on international duty that gives Harris a dilemma at left-back. He could start Tony Craig there and bring in Sid Nelson to partner Byron Webster. Eighteen-year-old Noah Chesmain is also an option to make his full league debut after impressing against West Brom on Tuesday night.
With Ferguson unavailable and Jimmy Abdou also with Comoro Islands for their Africa Cup of Nations qualifier in Uganda this weekend, Harris could give Calum Butcher his first start, with Ben Thompson on the left of midfield.
Steve Morison and Aiden O'Brien scored eight goals between them in August and will continue their partnership up front if Gregory misses out.
Bradford are unbeaten since the 3-1 defeat to Millwall in the first leg of last May's play-off semi-final but boss Stuart McCall has his own selection problems to contend with on Saturday.
Midfielder Josh Cullen is with the Ireland U21s, while defenders Tony McMahon, Stephen Darby, Rory McArdle and Nathan Clarke could all miss the game through injury.
Romain Vincelot, signed as a midfielder from Coventry, could continue in the centre of the Bantams defence.
Striker James Hanson, who has played only three games this season, trained on Thursday and McCall hopes to have him available to face the Lions.
McCall signed 12 players in the summer and the two who arrived on transfer deadline day, attackers Haris Vuckic and Marc McNulty – who has already faced Millwall with Sheffield United this season – could make their debuts for their new club at The Den.
Millwall record against Bradford:
Won 18 Drawn 16 Lost 10
Probable Millwall team:
Millwall: 4-4-2: Archer; Romeo, Webster, Nelson, Craig; Worrall, Butcher, Williams, Thompson; O'Brien, Morison.
Millwall 21/20 Draw 23/10 Bradford 13/5
Image source: ©Millwall FC