Barrie McKay’s wonder goal made it an unhappy return to the Championship for a dominant Millwall side.

The Lions could’ve scored six or seven at a packed-out City Ground, but failed to put away their openings. Lee Gregory wasted their best chance, missing an open goal early on in the second-half.

And McKay’s strike just before the break was enough to sink Neil Harris’ men, who will feel extremely hard done by.

Harris handed starts to summer signings Conor McLaughlin, Jake Cooper, James Meredith, George Saville and Jed Wallace. 

Millwall nearly took the lead through one of their new arrivals in the sixth minute when Gregory cut the ball back to Saville, whose shot trickled inches wide of the post.

And the Lions came even closer to scoring again after Steve Morison hit the crossbar. The veteran striker volleyed Cooper’s knock-on against the woodwork from close-range.

Millwall continued their dominance as the first-half wore on, and Forest goalkeeper Jordan Smith had to get down low to deny Gregory.

The Lions finally had some defensive duties to carry out, though, when Cooper blocked Daryl Murphy’s goal-bound shot. And it shortly followed with Jordan Archer making his first save of the evening, getting behind a swerving Ben Osborn strike.

League One’s most prolific partnership from last season combined well in the 41st minute as Gregory played a one-two with Morison, but the former’s effort was too tame.

And just a minute later, Forest new boy McKay went up the other end and his 20-yard screamer beat Archer to give the hosts the lead against the run of play.

Millwall could've been two down within seconds of the restart, but had James Meredith to thank after the Aussie put his body on the line to block Ben Brereton’s effort.

Gregory, guilty of wasting opportunities in the first-half, missed the best chance in the 51st-minute. Smith threw the ball straight to Morison, who unselfishly teed up Gregory, but the former Halifax man somehow missed the target with Smith away from his goal.

Millwall wasted another golden opening as Morison played Wallace through on goal - and Smith denied the winger with his legs.

Morison had the ball in the back of the net in the 77th minute, but referee Peter Bankes disallowed the goal for a possible push in the back.

And to sum up the way the game went for Millwall, substitute Fred Onyedinma put his header wide from three yards out in injury time.

Millwall (4-4-2): Archer, McLaughlin, Hutchinson, Cooper, Meredith; Wallace, Williams (Elliott, 83), Saville, O’Brien (Onyedinma 67); Morison, Gregory (Ferguson, 77).

Subs not used: King, Craig, Webster, Thompson.