And, after Lawrence was sent-off in the 80th minute, Johnson scored again to give Forest all three points.
“I think it was a totally different game to Walsall and our supporters can go home at least having seen a group of players totally committed, giving their all,” McGhee told the Millwall official club website.
“For an hour we looked like the team that deserved to win the game but things conspired against us.
"The misfortune we suffered was because the referee didn't see the handball just before they levelled and then we did ourselves no favours when Matt Lawrence was sent off.
"He should never have put himself in that position - it was a bit of poor defending, naive and it cost us the game."