Millwall escaped another late two-goal collapse as Jake Cooper and Shaun Williams scored against Derby County to secure their first Championship win this season.

Substitute David Nugent scored within five minutes of coming off the bench after the Lions netted twice during the first-half.

But despite threats of a second, the hosts got their first three points on the board following Middlesbrough’s late comeback on opening day.

That is now five points from a possible nine for Millwall in their first three league fixtures, while Frank Lampard suffered his second-straight defeat.

Here are five things we learned…

A dominating first-half – but a worrisome second-half

The Lions heaped pressure onto Derby County early on and, within the first half-hour, the visitors looked very uncomfortable.

As well as being two goals down inside 20 minutes, it appeared the tie was going only one way.

That wasn’t the case after the break, though.

Nugent’s strike turned the tide and Millwall’s counter-attacking exit plan lacked the execution it desperately required.

Could the substitutions have come sooner or been different?

Harris’ decision to withdraw Lee Gregory and Jed Wallace was a little surprising, and given perhaps they warranted being implemented sooner.

Steve Morison looked fatigued and in need of coming off, so when his strike partner came off instead it was a little surprising – particularly for fans.

With Ryan Tunnicliffe and Shane Ferguson coming on with roughly five minutes remaining, it’s arguable whether they would have been better done earlier on.

Shaun Williams was the star man in the midfield

Harris entrusted the 31-year-old with subduing Derby’s creative influence in midfield, and it worked effectively.

But not only that, he went on to score and grab an assist in what proved to be decisive moments for the team’s first three points this season.

Following that lengthy injury layoff last season, it’s good to see him back in first-team action and looking just as effective as before.

Some Derby players had a miserable day at the Den…

Martyn Waghorn received a frosty reception from supporters all match during the defeat to Millwall.

The former, who is one of Lampard’s raft of new signings, was not received warmly by fans following his short stint at the club in 2013.

He was eventually replaced by Nugent but had a torrid time of trying to get past Cooper and Shaun Hutchinson, culminating in an afternoon to forget.

Another scalp against the big boys for the league’s perennial underdogs

Teams know what to expect when they go up against Millwall, particularly away from home, but are still watchful of bringing back all three points.

So when the Lions take those three points away, it serves as a reminder – and Derby’s defeat to the Lions evokes similar sentiments.

If a similar but more polished performance can be repeated at home to fellow promotion hopefuls Swansea City then it, again, sends a stern message of what the club things of being tipped for relegation.