Suso made 14 Premier League appearances as a teenager for Liverpool during the 2012-13 campaign, but after going out on loan to Almeria the following season he would not play for the Reds in the English top flight again.
Milan are enjoying a revival under new coach Vincenzo Montella, sitting second in the league behind Juventus after their 4-1 win over Empoli on Saturday having failed to crack the top six in the previous three seasons.
Their tally of 29 points from 14 games during the current campaign is their best since 2010-11, when they collected 30 and were crowned champions by a six-point margin.
And leading their charge in attack is Suso, who has been involved in Milan's last seven goals - scoring four himself and creating three - to help the Rossoneri to two away victories and a 2-2 draw against rivals Inter.
The Spaniard is even drawing comparisons to current Liverpool star Philippe Coutinho thanks to his tendency to cut inside from the right flank, with Coutinho known for a similar style on the left wing.
And now the Brazilian is facing a spell on the sidelines after being taken off injured during the Reds' win over Sunderland on Saturday, Liverpool might be wishing they had never let Suso go.