Loanees rarely face their parent club, but with the news that Marco Asensio is set to line up for Aston Villa against Paris-Saint Germain, we take a look at some famous examples of players haunting their parent side.
It took £116m to prise Philippe Coutinho away from Liverpool in 2018 but after just one season, the move wasn't going to plan.
Bayern Munich came knocking, a loan fee was agreed and the Brazilian made the switch to Bavaria.
When the two sides drew each other in the UEFA Champions League quarter-finals the following season, it was written in the stars for Coutinho to have an impact.
The German side found themselves 5-2 up and with 15 minutes to play, Coutinho was sent onto the pitch.
He promptly bagged a brace before adding an assist to further rub salt into the wounds.
The resulting 8-2 loss remains Barcelona's heaviest-ever European defeat.
With 100 goals in the famous Real Madrid colours, Fernando Morientes was a dependable forward for Los Blancos.
The arrival of Ronaldo complicated that somewhat and after falling out of favour he joined Monaco on loan.
An instant hit at the French side, Morientes was in fine form by the time the UEFA Champions League quarter-finals rolled around and it was decided that the Spaniard would face his parent club.
What a tie it turned out to be.
5-5 the final scoreline, Morientes scored home and away to see his club through on away goals.
The former Spain international would end the season as the competition's top goalscorer, but unfortunately his final ended in defeat to Jose Mourinho's Porto.
Struggling to get regular minutes in the Dutch capital, Jan Vertonghen was sent to struggling RKC Waalwijk on loan in 2006/07.
RKC Waalwijk's season did end in relegation, but Vertonghen would still have a major say in the title race.
With four matches left to play, Ajax travelled to Waalwijk in what ought to have been a routine win.
The home side frustrated Ajax, holding them to a 2-2 draw with the Belgian loanee popping up with a crucial goal.
His parent club would go on to finish second in the Eredivisie, missing out on the title on goal difference.
The goal difference total? One single goal.
Famed for winning a league title in each of his first 11 seasons as a professional, Kingsley Coman joined Bayern Munich on a two-year loan from Juventus in August 2015.
It wasn't long before the Old Lady were made to rue their decision.
With the clubs set to face each other in the UEFA Champions League last-16, Coman was poised to go up against his parent side.
The scoreline read 2-2 after the first leg, but two early Juventus strikes meant that goals from Robert Lewandowski and Thomas Muller were needed to send the game to extra-time.
Enter Coman.
The teenage Frenchman bagged the game-deciding goal as Bayern ran out 6-4 winners on aggregate to reach the quarter-finals.
Real Madrid get their second unfortunate entry into our list after Alvaro Morata came back to haunt his parent club whilst on loan at Juventus.
If not by sheer volume of goals, Morata did score at vital moments and his stage this time was the UEFA Champions League semi-final.
Drawn against Madrid, it took the Spaniard just eight minutes to slot the ball past Iker Casillas in the first leg.
The game ended 2-1 to Juventus, with strikes from both Cristiano Ronaldo and Carlos Tevez setting the tie up perfectly for the second leg.
Ronaldo, as he did so often, opened the scoring at the Santiago Bernabeu.
But up popped Morata. The Spaniard rounded-off a brilliant team move to dump Los Blancos out of the competition and send Juventus to the final.