Fellow striker Shaun Batt is also struggling (hamstring) but Neil Harris, Gary Alexander and Jon Obika are on hand to deputise.
Huddersfield manager Lee Clark told BBC Radio Leeds:"Our strengths are that we create lots of opportunities, we've scored 100 goals in all competitions and we try to put the opposition under pressure.
"We know it's not going to be easy - they (Millwall) have been built up over a period of time under Kenny (Jackett), who's built a very strong, athletic, physical team.
"They were very, very close to getting one of those automatic promotion places, so we know it's not going to easy, but I think the respect is passed over to each other."
Huddersfield striker Jordan Rhodes told BBC Radio Leeds:"If someone had said to me at the start of the season that I'd have played as many as games as I have and scored 23 goals, I would have settled for half of that.
"For it all to happen is a bit of a fairytale and a dream, and I love coming into work and walking out on that pitch on Saturdays and Tuesday nights.
"There's plenty of hard work to be done and Millwall are a terrific side - they're very well organised and well drilled, so let the best team win really."
BIG-MATCH FACTS
Head to head
• There is nothing to choose between these clubs. Huddersfield and Millwall have each won 16 of their 37 competitive meetings, with five drawn.
• Both league meetings this season were won by the club playing at home.
Huddersfield Town
• Finished in sixth place, five points inferior to Millwall. They netted 82 goals, making them the top scorers of the four clubs in these play-offs.
• In the 19 years since the play-offs have been in the current format, the club finishing four places outside the automatic promotion spots has been the most successful - promoted to the second tier seven times, including Scunthorpe last season.
• Lost their last game of the regular league season, away to Exeter after winning the previous four, with an aggregate score of 13-4.
• Won their last four home league games, and unbeaten in five at the Galpharm since defeat by Norwich on 13 March; their only loss in 11 on home turf.
• Just ended their sixth successive season at this level, and not played in the second tier since 2001.
• Hoping to win promotion through the play-offs for the third time after successful campaigns in 1995 and 2004.
• This is Lee Clark's first experience of the play-offs as a manager.
Millwall
• Finished third, one point outside the automatic promotion places.
• Won 10, drew three and lost two of their last 15 games in the regular league season.
• Have just ended their fourth season in League One after relegation in 2006.
• This is their sixth attempt to win promotion through the play-offs; lost in the semi-finals on four occasions, until defeat to Scunthorpe in last season's League One final at Wembley.
• In addition to last season's disappointment, Kenny Jackett also lost a play-off final as a manager in 2006, when Barnsley won on penalties to deny Swansea promotion to the Championship.
• The club finishing immediately outside the automatic spots in this division, has gone on to gain promotion through the play offs on five occasions since 1991, including in two of the last three seasons.
Source: BBC Sport
Source: BBC Sport