MILLWALL boss Neil Harris felt an injury picked up by Lee Gregory late on against Wigan played a part in his side conceding a last-minute equaliser.
Harris brought on Ben Thompson for Aiden O'Brien in the 83rd minute just before Gregory fell under a challenge.
With all three substitutes used the striker was treated on the pitch by physio Bobby Bacic but stayed on despite being in some discomfort.
Millwall held out until the 92nd minute when the ball broke to Wigan substitute Will Grigg and he fired in to keep his side's unbeaten home record intact.
"Losing Lee Gregory, being a passenger on the pitch really, was difficult because we're a player short," Harris said. "It was a shame because he played really well. It was just after the third substitution when he got a whack so we virtually played with 10 men for a period of time.
"Fair play to him, he didn't want to come off and that shows his character as a person. But it's difficult when you're playing against a possession team with 10 men.
"We're frustrated with the last goal because in our penalty area we don't quite get the break. The ball falls to Will Grigg, he hits it and it hits two of my players before going in when it could have gone anywhere."
Gary Caldwell's side dominated possession in the first half without testing Jordan Archer in the Millwall goal, but Harris felt his side created the best two opportunities in the opening 45 minutes.
He said: "We were happy for Wigan to have the football in the first half and pass sideways and backwards and as much as they had all the possession in the first half we had all the chances, so we weren't overly concerned.
"We adjusted slightly at half-time to stop the threat coming down the left side. I was frustrated with the first goal because we were in possession of the ball and we give it away.
"But then we made the subs to get us further up the pitch, be more aggressive in our pressing and we certainly did that."
Harris rested Fred Onyedinma and Steve Morison but both were introduced in the second period with Millwall chasing the game.
And Onyedinma rewarded that decision by slotting home Millwall's eaqualiser.
"I learnt last week that it's hard especially for our attacking players to play three games in a week," Haris said. "Fred definitely looked like he might have needed freshening up.
"I play him because I trust him, he makes such an impact for us. He has a moment of brilliance in a game and it changes the game sometimes.
"(Tuesday) night I felt we needed something a bit different and with Lee Gregory and Ed Upson coming in it gave us a different outlet and fresh legs.
"But being able to bring on Steve Morison and Fred is a big bonus."
After Mark Beevers had put the Lions ahead Wigan forced another corner in added tie and though Archer miscued his punch Harris felt his goalkeeper was right to go for the ball.
"Having seen it back I'm not massively disappointed," he admitted. "We're frustrated with both goals, they were avoidable. But I think for the second one the goalkeeper makes the correct decision but doesn't quite execute the punch properly and the ball falls straight to their best striker.
"It could have easily not gone in our net, but I'm sure Gary would say the same about our two goals as well.
"We showed great spirit. In the first half we stayed strong, without being under massive pressure, but we had to work tirelessly to deny goal-scoring opportunities.
"The boys were confident at half-time we would get more chances in the second half and try and be solid and see the game out at the back.
"But it's a point gained though, definitely."