When Monaco and Manchester City embarked upon a sensationally riotous Champions League last-16 affair in 2017, a livewire forward with a combination of technique and pace to leave the most seasoned defenders utterly mortified scored in both legs as the Ligue 1 side went through 6-6 on away goals.

That young man was Kylian Mbappe. But it was also, in a losing cause, Leroy Sane.

Four years on from a knockout tie that marked out both players as potentially dominant figures for the decade to come in European football, each had points to prove at the Parc des Princes on Tuesday.

Mbappe was looking to add to the argument that he is the finest player in the world right now, Paris Saint-Germain's talisman in their quest for elusive continental supremacy. 

Sane was trying to prove he belongs at Bayern Munich.

In all competitions this season, Mbappe has 33 goals and 10 assists, following up his brace as PSG edged Bayern 3-2 in the quarter-final first leg by scoring one and setting up another in a 4-1 win over Strasbourg. 

Only Robert Lewandowski (50) – oh, how heavily his absence weighed upon the Bavarian giants' eventual exit – and Harry Kane (45) have more than Mbappe's 43 goal involvements among players in Europe's top five leagues.

Sane has scored four times in the Bundesliga and not at all in the league since January 3. 

If Serge Gnabry was not undergoing a period of coronavirus isolation, it is doubtful the winger would have had the chance to atone for an ineffective first-leg showing.

It pays not to be ineffective when the remaining array of attacking talent are cranking merrily through the gears. 

Mbappe and Neymar grab the limelight but, flanked by Angel Di Maria and Julian Draxler, the entire PSG forward line was irresistible during the first half.

One piece of skill to humiliate Benjamin Pavard might mean Mbappe apologising profusely the next time France's national team gets together. 

However, as in the first leg, Bayern were in no mood to drop deeper and rob Sane, Kingsley Coman and the rest of a platform to lay siege to the PSG goal.

Similarly, the hosts would not instantly go long. 

They would play through the ravenous press because Mauricio Pochettino says so and Leandro Paredes – both as easy on the eye and robust as a polished marble slab – relished the challenge in holding midfield.

When it worked, their magnificent forwards were away; when it didn't, PSG were incredibly vulnerable. The opening 20 minutes felt like two heavyweights swinging big punches while balancing on highwires.

Neymar's soft feet and underestimated hard edges were at the heart of some of the most eye-catching moments. A wonderful body swerve left David Alaba in his wake and he curled against the bar. Then he hit the post.

The tempestuous Brazilian superstar often seems to think the fates are conspiring over the course of 90 minutes. 

When Bayern bounced off the ropes for Eric Maxim Choupo-Moting to scramble home against his former club, making it 3-3 on aggregate, it was tempting to think Neymar might actually have a point.

Sane forced Keylor Navas into a sharp save in first-half stoppage time and he threaded a superb ball through for Thomas Muller to almost put Bayern ahead in the tie after the hour.

By that time, Neymar had produced more outrageous skill and agonisingly failed to turn home with the goal gaping. 

Jerome Boateng nonchalantly backheeled the loose ball behind for the corner, apparently so mesmerised by the fancy footwork that he had to join in.

Boateng wasn't the only jack of all trades as Neymar tore back into his own half after Sane skipped past Paredes. He didn't tackle him. Mbappe did.

It was an utterly colossal contest. Mbappe strayed just offside before he throttled one into Manuel Neuer's net, the Germany goalkeeper somehow seeing out a clean sheet that will be scant consolation.

Then, in stoppage time came Sane's moment. He had found PSG replacement left-back Mitchel Bakker very much to his liking during the final half hour and darted into space down the right channel. 

There was time to cut back on to his favoured left foot and pick the pass for the winning goal.

Sane mishit the cross, the unflappable Keylor Navas grasped it and PSG were out of the woods. 

After another Champions League classic settled on away goals, he and Mbappe remain on very different trajectories.