Massimiliano Allegri accepted his share of the blame for Juventus' 1-1 draw with Milan, but also felt his players lacked focus as they slipped into the Serie A relegation zone.
Alvaro Morata put Juve ahead in Sunday's clash at the Allianz Arena inside four minutes with his side's earliest goal against Milan in Serie A since February 1996.
Juve were on top for the rest of the first half, but they dropped off after the interval and were punished by Ante Rebic's header 14 minutes from time.
The Bianconeri are winless in their opening four games to a league season for just the fourth time in their history and find themselves 18th in the 20-team division.
Allegri took off Morata, Juan Cuadrado and Paulo Dybala in a 13-minute period prior to Milan's leveller, with Moise Kean, Federico Chiesa and Dejan Kulusevski brought on.
And the experienced coach, who has one win from five matches in all competitions since returning to Turin, is annoyed that his side could not see out a much-needed victory.
"Tonight I'm left angry," he told DAZN. "The team played well in the first half and only conceded one long-range shot, but in the end we could have even lost the match.
"That's despite being in control until the equaliser. Unfortunately we lost attention and determination. We have to improve.
"The thing you have to quickly learn is that in these games, the final moment you have to be tough. You have to remain concentrated, determined and focused.
"We know we have to play better, and that is part of the growth of some players. But I also made a mistake with the changes today – I should have brought defensive players on.
"The likes of Dybala and Morata perhaps could have made themselves more available when on the field, but the last 15 minutes is what makes me angry."
Allegri's side have already dropped seven points from winning positions this season, compared to 10 such points in the whole of 2020-21 under Andrea Pirlo.
Juve have now conceded in 18 successive Serie A games and could easily have shipped a second goal late on as Pierre Kalulu forced Wojciech Szczesny into a big save.
"Luckily the referee whistled when he did because otherwise we may have lost," Allegri said. "Nobody remembers the good performances because we lost two points in the end."
The draw – just the second in the last 25 league meetings between the sides – leaves Juventus eight points adrift of early pacesetters Inter and Milan in the top two.
Asked if his side are already out of the title race, six-time Scudetto-winning boss Allegri said: "It was important to take a positive result against Milan today.
"If they'd have won they would have pushed us further back. The draw leaves their advantage unchanged.
"The problem is that winning a game is one thing; winning a league is another. It means not conceding goals due to errors like we saw today.
"There were positives, mainly in the first half, but we should have suffered more and been ready to defend tooth and nail. You have to take the win even if it's ugly."