In 2015, Manchester City visited the Camp Nou in the last 16 of their Champions League second leg clash and Messi put on a show.
He was the busiest player on the night and James Milner was the major victim of his class when the midfielder was sent for a hotdog thanks to an audacious nutmeg.
Picking up the ball on the right touchline, Milner tried his best to retrieve it back before being left red faced by Messi.
Guardiola, having seen it so often when he was his manager, watched on in amazement.
A 1-0 win on the night saw Barca through to the quarter-final in a season that ended with them being crowned European champions.
A few years later, when playing for Liverpool, Milner was asked to pick his ultimate XI, with Messi understandably making the cut.
"I've played against against him a few of times in the Champions League and most people probably remember the nutmeg on myself," he said.
"I won't be the first and I won't be the last who got megged by him."
Messi and Guardiola spent arguably the best period of their career's together until the boss left in 2012, winning Europe's premier club competition twice, as well as multiple league titles.
Guardiola will be hoping Messi isn't up to his old tricks tonight, though, when his Man City side travels to the Parc des Princes in search of three points in their Group A clash.
Asked how to stop such a strong side that, as well as Messi, includes Kylian Mbappe and Neymar, Guardiola said it will be difficult.
"With this amount of quality I don't know how to stop them," he said in his press conference ahead of the showdown.
"They're so good. This amount of talent makes it so difficult."