When the fourth official's board went up in the 68th minute of Bayern Munich's Bundesliga game against Bayer Leverkusen in December, Jamal Musiala's number flashed up.
The then-17-year-old was being sent on by Hansi Flick to help find a winner with the game locked at 1-1.
The other number on the board came as a surprise, not least to Leroy Sane, the player Musiala was sent on to replace.
Sane had had a chance to score earlier in the game after being set up by Robert Lewandowski, but even though he was not performing at his best, he did not expect to be taken off.
The Germany winger had been on the pitch for just over half an hour, coming on as a substitute for the injured Kingsley Coman before being substituted himself.
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Flick's comments afterwards were telling: "When we make substitutions, we have to do it sensibly. If you see the second half, Thomas Muller is indispensable, Serge Gnabry improved in the second half, that's why I substituted Leroy Sane.
"We had to react like that because there was no other option."
The Bayern boss has been a harsh taskmaster all season with regards to his summer signing. In November, Sane was singled out by the coach for another poor showing, despite Bayern beating Red Bull Salzburg 3-1 in the Champions League.
"We are pleased with him, but it is important that when he starts a game, he gives 100 per cent,” Flick said. “We are working on that.
“Like other players, he unnecessarily lost the ball a couple of times against Salzburg and, in some instances, he didn't quite pursue one-on-ones. There are reasons for it, and we talked about that. He will try to do better next time.”
Doing better is something Bayern's bosses expect from Sane, after spending an initial €49 million (£45m/$55m) to sign him from Manchester City, with that amount potentially rising to €60m (£55m/$67m) through add-ons.
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Sane was signed to be the final piece in the club's attack and help them retain the Champions League in a year when they won every single domestic and international trophy on offer.
Initial signs were very promising, with a goal and two assists on his Bundesliga debut in an 8-0 over Schalke. However, in 25 league games since then, he has scored just three more times, and last scored in the Bundesliga on January 3 despite playing every game in 2021.
Bayern look likely to win the league again this season, which would be their ninth title in a row, but they are already out of the DFB-Pokal and their Champions League hopes are hanging by a thread after a 3-2 home defeat to Paris Saint-Germain last week.
While injury affected Sane's bedding in period at Bayern and can be blamed for poor performances in November and December, the 25-year-old is fully fit now and has no such excuses.
On Tuesday evening in Paris, they need him to be the player they were willing to pay €60m for to live up to the hype.
In the first leg, Bayern attempted 31 shots as they dominated all the stats apart from the scoreline. Sane had just two shots, and neither of those were on target.
As well as that, he played just one key pass, the fewest of any of Bayern's attackers - even defender Jerome Boateng had more and he played just over half the game before going off injured.
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If Sane does not shine on Tuesday, Bayern's season will be a disappointing one. Finishing with just the league title is not good enough for a club of their standing.
Flick has given Sane a vote of confidence ahead of the tie, saying: "Leroy is a player who makes the difference, absolutely. He's been doing very well in the last few weeks. I'm very satisfied with him."
The Bayern coach has no other choice than to put his faith in Sane, especially with Gnabry absent due to coronavirus and Coman returning from injury.
Top scorer and currently the world's best player, Lewandowski, is not in the squad either. He also missed the first leg, where he surely would have converted at least one of Bayern's 31 shots.
"We had many chances in the first leg, but we weren't efficient. We have to do better," Flick insists.
Bayern have to do better, and Sane definitely has to step up his game to live up to his price tag.
