NEIL Harris admits recent fixtures have been "tough" on Lee Gregory and Aiden O'Brien and says he will assess their fitness levels ahead of tomorrow's trip to Blackburn.
Gregory and O'Brien have started all seven of Harris' games in charge, both scoring once, but felt "absolutely shattered" during the latter stages of Saturday's draw with Cardiff.
Millwall head for Ewood Park on Tuesday for their fourth game in ten days, knowing that a win would close the gap on fourth-bottom Rotherham to just one point.
And Harris must decide whether to ask Gregory and O'Brien, whose movement and energy has been key to recent results, to put in the hard yards once again.
The strike duo were withdrawn after 75 minutes against the Bluebirds as heavy legs took their toll.
Ricardo Fuller, Magaye Gueye and Gary Taylor-Fletcher all came off the bench and are pushing to start, while Paris Cowan-Hall, an unused sub, is also available.
"Lee and Aiden do not stop running." Harris said. "They've both scored for me but it's not the goals that everybody is appreciating.
"And when I talk about everybody, that's not just the fans and the staff but their teammates. The other players appreciate what they do for the team.
"Given where we are as a club and the position we're in, we need to get footholds in games, be solid and build a foundation – and those two are giving us that.
"It's been tough for them.
"I took them off because they were absolutely shattered, both got knocks and both have had knocks over the last few weeks, and they just keep going and going.
"The physio keeps patching them up but it's not easy. And we've got other players chomping at the bit to have a game, so there is definitely competition for places."
Fuller in particular made a strong impression off the bench, using his strength and speed to create a late chance for Taylor-Fletcher.
Harris added: "I don't think it's just Ricardo's impact on Saturday, it's the way he's been around the whole club since I came in.
"He's been in squads and out of squads – we left him out at Brentford and then he had a niggling injury – but he's back in the fold and looks like a man who's hungry to play.
"He's a top player, a good pro and the way he communicates with the younger boys is outstanding."
Cowan-Hall is yet to feature since returning from an ankle ligament injury but has been included in squads to face Wigan and Cardiff.
"We've still got to be careful with Paris," added Harris.
"It's no secret we've rushed him back before and he's broken down twice, and we've rushed him back this time to get him back in the fold.
"He's been back in the squad but that wasn't neccesarily because he was ready to start a game. It might have been only ten or 15 minutes.
"But with every few days that goes past, he gets another training session or two.
"I think we're getting to the stage where we can consider him for a start but we're certainly getting more comfortable with using him as an impact sub."