For Tottenham, Wednesday's Champions League defeat to Juventus was a sickener. It must have felt like running head first into a brick wall.
There was the concrete presence of Georgio Chiellini, who was impassable at the heart of Juve's defence. There was the challenge of beating a club part of the old-money elite, who always find a way to win at this level.
Tottenham manager Mauricio Pochettino felt the defeat was a case of bad luck and missed chances.
In isolation, there was no shame in losing 4-3 to Juventus over two legs but the result was part of a wider pattern of dominance by Europe's established class, who continue to show that DNA is more important than anything.
On Tuesday, Paris Saint-Germain, the ultimate new-money club, fell before the semifinals for the sixth year running, losing 5-2 on aggregate to a Real Madrid side who are a pale imitation of the team that beat Juve in last year's final. Chiellini, for one, could see a connection between the two results.
"We believe in the history," said the centre-half after Juve's 2-1 win at Wembley. "Also, yesterday in the game between Real Madrid and Paris, the history, it's important, and the experience is important, and we used our skill to arrive at the win."
PSG and Spurs have climbed the ladder with very different approaches -- PSG by spending lavishly, Spurs by building steadily -- and yet for both clubs it still not enough. Between them they have four of the most valuable assets in football in Kylian Mbappe, Neymar, Harry Kane and Dele Alli but they both remain short of what is needed -- be it mettle, quality or, as Chiellini believes, simply experience -- to upset the established order.
In the early rounds of the group stage, this season's Champions League looked like a more open shop than in any of the previous five or six years. Real Madrid, Juventus and Bayern Munich faced new domestic challenges with ageing stars, while Barcelona's predatory place in the food chain had been upset by Neymar's transfer to PSG.
This view was solidified by Real's defeat to Spurs, Bayern's hammering at PSG and Juventus' stuttering progress through their group. And yet when it mattered, those swashbuckling wins for Spurs and PSG counted for nothing as the elite found a way to win again, without playing well.
Meanwhile, Manchester United and Barcelona, also members of the old guard, go into their second legs in strong positions, despite going through the motions away from home.
As it stands after half of the round-of-16 matches, only Manchester City, who beat Basel 5-2 on aggregate, look capable of denying one of regulars the Champions League trophy, having reached the semifinal two years ago. And that was after four years of underachievement in the competition.
While PSG's Champions League failures seem to be rooted in psychology and their dominance of a weak domestic league, Spurs will hope the brick wall is not topped by a glass ceiling. Asked how they can take the next step in the Champions League, Pochettino's message was clear: keep moving in the same direction.
Spurs have improved inexorably from last season's campaign, when they beat only CSKA Moscow, and Wednesday evening felt like the kind of chastening sucker-punch they can only learn from.
"We're so young," said Son Heung-Min, who scored their goal at Wembley. "Remember last season when we had the problem with the Champions League at Wembley? This season, no-one can say anything. Everyone didn't think in the group stage we'd be through but we're through and we played very well against Juventus."
The problem for Spurs is that taking the next stride forward in Europe could be a much longer process, as Manchester City have shown and PSG are still showing. Learning how to win when it really matters does not happen overnight.
Pochettino often talks about Spurs' development as a "process" that could take years and the defeat to Juve underlined this point. The manager hopes it will be considerably accelerated when the club has finished building its new stadium and moves there for the start of next season.
That task is nearly finished. Spurs, though, have only just begun building a wall of their own.