Ian Baraclough blamed a sluggish start for Sunday's disappointing Nations League defeat to Austria.
Northern Ireland were slow out of the blocks and trailed to Michael Gregoritsch’s clinical header three minutes before the break.
And despite showing some improvement in the second half they fell to a 1-0 defeat in front of 600 fans at Windsor Park.
Austria's victory was more comfortable than the narrow margin of victory would suggest, and on another night the result would have been more definitive.
From the highs of Sarajevo three days previous to the dejection of another Nations League defeat, Baraclough refused to offer any excuses as his side remain bottom of their group.
"I thought we were passive in the first half. Every skirmish and 50/50 Austria came out on top of," he said.
"We put more pressure on them in the second half. I thought we engaged higher up and forced them into mistakes and created a few chances from that.
"But we can't afford to start games the way we did and expect to win, whether it is home or away. We need to be more competitive."
Thursday's marathon test against Bosnia and Herzegovina saw Baraclough make five changes to his starting line-up for tonight's game.
Jordan Jones, Kyle Lafferty and Gavin Whyte all started, alongside goalkeeper Michael McGovern and defender Conor McLaughlin.
"I didn't want to make wholesale changes - nine, 10 or 11 changes. It can completely distort the team," Baraclough added.
"I was asking players to go to the well again and dig deep. Maybe Thursday did have an impact, but we don't want to use excuses.
"The other night is what it was. One hundred and twenty minutes plus penalties, it was physical and emotional.
"But we don't want to put that as an excuse."
Baraclough will need his players to "go to the well" once more on Wednesday when they travel to Norway for their third game in the space of seven days.
"No one has ever played three international games back to back. It is a fact finding mission, and during these Covid periods you are trying to work and plot ways to deal with it," he said.
"You have to find a way as we have triple headers next month and again next March and September, I believe. So it is becoming the norm.
"We can't come in after 45 minutes and speak about being more aggressive. That needs to be there from the start. We have to find that way."
Meanwhile, winger Jordan Jones says the players will have to recover quickly as they prepare for another Nations League game on Wednesday.
"We have to recover and go again," the Rangers man said.
"All the boys were buzzing after Thursday night. It was a big night, going all the way to penalties. Everyone was on a big high, and then tonight we have a bit of a low.
"But we have to pick ourselves up. We were a lot better in the second half tonight, but we can't have any excuses. We didn't perform tonight.
"We were too far off it in the first half. We didn't press them enough and we were one or two yards off it.
"The message was to press with more intent and try and get them on the back foot. I think we did more of that in the second half, but not enough to get an equaliser."
