Roberto Martinez warned Wigan they must learn the lessons from their profligacy in front of goal after falling victim to an FA Cup giant-killing at the hands of Notts County.
A combination of poor finishing and excellent saves from County goalkeeper Kasper Schmeichel meant Wigan failed to hit the target against their Coca-Cola League Two opponents despite creating a host of chances.
Latics striker Jason Scotland - who had been guilty of squandering several opportunities in Saturday's defeat to Everton - set the tone early on at the DW Stadium after shooting straight at Schmeichel when put through one-on-one in the 11th minute.
The visitors eventually took advantage through Stephen Hunt's 75th-minute header with Gary Caldwell's own-goal making it 2-0 three minutes later, and Martinez admitted Wigan's wastefulness had left them vulnerable to an upset.
"I think we all knew what to expect in this sort of game," Martinez said.
"They are going to get a lot of players behind the ball and work extremely hard, but we created a lot of chances.
"Probably the first one (Scotland's) was a clear example of the game. In these situations you need to score the first goal and that changes the game completely.
"You could see that we were getting frustrated and even though we started well in the second half, we couldn't get the first goal.
"When that happens, there is that risk and you know you have a lot to lose. You are at home and the upset is on the cards, and I think we felt that way.
"But today is a day to congratulate Notts County and allow them to enjoy a huge achievement in going through to the fifth round.
"For us, it is to learn a few lessons, knowing that we have been a little bit low in terms of confidence in front of goal."
The match attendance was a disappointing 5,519 but County caretaker boss Dave Kevan was delighted for the travelling fans who made the journey from Nottingham to see their team set up a tie against Fulham in the last 16.
"It's a fantastic night for everyone involved," said Kevan.
"To see our supporters celebrate a victory like we've had there this evening makes everyone very proud and we have a fantastic group of players.
"Everyone has really worked very hard and tonight is a very, very memorable night for us all.
"We expected a very tough game and that's exactly what we had. Credit to the lads, who worked very hard.
"We surrendered a fair amount of possession, as you would expect against a very good Premier League team that play fantastic football.
"But the lads were very disciplined and very concentrated and when they did break through us Kasper was there to make some fantastic saves."