The boos inside the Tottenham Hotspur Stadium were not overpowering but they were clearly audible. Following a stuttering start to the season, a third consecutive home defeat to north London rivals Arsenal was difficult to stomach for watching fans.
Ange Postecoglou came out fighting afterwards, pointing out in his interview with Sky Sports that he "always" wins things in his second seasons. "I don't say things I don't believe in," added the former Celtic boss. But the optimism of fans is being tested.
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Mid-table form a major worry
Postecoglou argued, with some justification, that Tottenham's displays across their first four games of the season merit more than four points. But Spurs were poor on Sunday and, even when they do perform, their inability to capitalise is a long-standing issue.
Take away the first 10 games of last season, when they won eight games under their new head coach, taking 26 points from a possible 30, and their record is alarmingly poor, with a total of only 44 points taken from 32 Premier League fixtures subsequently.
That points total has them ninth among Premier League clubs, sandwiched between Bournemouth and West Ham, over the course of almost an entire calendar year. They are 14 points off the team in fourth, Chelsea, and 35 points off leaders Manchester City.
Spurs have lost more games than they have won and conceded nearly two goals per game in that timeframe. Of the 17 ever-present teams, only West Ham, Wolves and Brentford have let in more. Only the latter two sides and Nottingham Forest have more losses.
This is no blip, in other words, rather an extended period of results akin to a mid-table team rather than a European challenger. And the worry is that they are worsening rather than improving. Spurs having only won three of their last 11 Premier League games.
Son among key players underperforming
Senior players are struggling, including Heung-Min Son. Leaving the stadium on Sunday, after a game in which the captain did not register a shot on target, fans could be heard questioning Postecoglou's reluctance to take him off.
Son scored twice in the 4-0 win over Everton in the previous game at the Tottenham Hotspur Stadium. But that fixture was one of only three out of the last 13 in the Premier League, dating back to the end of March, in which he has managed to find the net.
Cristian Romero is another example. The Argentina international had the home fans on their feet at one point in the second half when he produced two typically full-blooded defensive interventions in the space of a minute. But he continues to falter at key moments.
The lapse which gave Gabriel Magalhaes a free run at Bukayo Saka's corner for Arsenal's winning goal followed similarly costly errors in Tottenham's games against Leicester, when he allowed Jamie Vardy to equalise, and Newcastle, when he failed to track Alexander Isak.
Postecoglou talked about Romero setting an example for his team-mates to follow after Tottenham's 3-2 loss in Arsenal's last visit to the Tottenham Hotspur Stadium in April. But more recent evidence raises questions of his leadership and reliability.
Set-pieces woes continue
Postecoglou insisted Spurs dealt well with Arsenal's set-pieces before Gabriel headed the winner from Saka's inswinging delivery. But balls into the box had been causing unease all game. "We knew we could hurt them on set-plays," said Mikel Arteta afterwards.
It is not just Arsenal who have exploited Spurs' ongoing weakness from dead-ball situations. Gabriel's goal was the 18th they have conceded from set-pieces since the start of last season - the second-highest total among ever-present Premier League teams.
Again, the worry is that the situation has only worsened during Postecoglou's tenure. Spurs have now conceded a staggering 13 goals from corners in 22 games since the turn of the year.
It is partly down to personnel. Gary Neville bemoaned Guglielmo Vicario's inability to "dominate" his box. Romero's failure to properly challenge Gabriel was even more costly. But Arsenal's success with set-piece specialist Nicolas Jover shows coaching is key.
It does at least seem that Postecoglou is taking the issue seriously. Last season, he sparked outcry when he appeared to dismiss the importance of set-pieces. On Sunday, he was eager to change the narrative. "We work on them all the time," he said.
More work is required.
Signings under scrutiny
Tottenham's slow start to the season comes after a summer in which they were the fourth-highest spenders in the division, their outlay totalling £133.5m on four permanent signings.
The most expensive of them, Dominic Solanke, a £65m recruit from Bournemouth following an excellent 18-goal season last term, is still waiting for his first in Spurs colours.
Against Arsenal, he worked tirelessly off the ball but dithered when presented with a golden opportunity following Ben White's poor pass in the first half, allowing William Saliba to get across and block his effort. It was one of only two efforts on goal from him all game.
Solanke still has time to prove he can be the No 9 Spurs crave, of course. He is only three games into his career at the club. But he is not the only recent signing under scrutiny.
Pedro Porro, for example, offers immense attacking value but his struggles against Gabriel Martinelli on Sunday were a reminder of his defensive shortcomings. James Maddison is still struggling for consistency. Brennan Johnson's blunt display was not his first. Vicario remains vulnerable from crosses and set-pieces.
Spurs have succeeded in lowering the age of the squad since Postecoglou's appointment. Sustainability and long-term success are the aims. But, with £385.5m spent across three windows, supporters are entitled to expect more in the here and now.
Style questions remain
Overhauling Tottenham's playing style, from the often-dour, reactive football produced under his predecessors, Antonio Conte and Jose Mourinho, was one of Postecoglou's main responsibilities when he arrived at the club last summer and he has delivered.
Spurs are transformed, stylistically. They play higher up the pitch and press more aggressively than any other Premier League side. There is a far greater emphasis on dominating possession. When it all comes together, it can be exhilarating.
The issue is that those instances of 'Angeball' at its most effective are becoming increasingly rare. Instead, an apparent reluctance to adapt his approach has come to feel like a problem.
The Arsenal game was just the latest in which they have struggled to translate possession into goals. Spurs have averaged more than 60 per cent of the ball in 10 of their last 13 Premier League games and yet only actually won four of those games.
Opponents are figuring them out, sitting back and soaking up pressure while knowing that, through their vulnerability from set-pieces and counter-attacks, chances will arise at the other end.
Postecoglou is prioritising the long-term. He talked of progress in his post-match press conference on Sunday, albeit while admitting there are areas which still need attention. But following the latest defeat, he has work to do to prove they are on the right path.