Grealish, 26, posted a story on his Instagram account where he was seen working hard in the Athens heat.
The England international had previously been carrying out several training drills on the Island of Santorini.
Prior to this, Grealish had attended former Aston Villa teammate Conor Hourihane's wedding, before heading to the Greek capital.
His hard work on the training pitch is clearly paying off, with the forward in fine shape, showing his broad physique, ahead of his return to Manchester.
Grealish had plenty of footballs out and was captured passing to a bench, before firing into an empty net, as he gets his shooting skills in up to speed.
City will start pre-season in less than a week and it seems as though their star was keen to get ahead of the game.
Manager Pep Guardiola will be happy to see the England star going through his paces, after he was previously pictured having plenty of fun on holiday.
It was certainly a change of scenery for the player, who had been relaxing in Las Vegas and Ibiza following the end of last season.
Grealish's holiday destination appeared to split the nation, drawing criticism from some, while others claimed there was nothing wrong with a young bloke letting his famous hair down.
He had also attended Harry Maguire's £500,000 French wedding in at the exclusive 13th Century Chateau de Varennes in Burgundy.
Grealish, a £100million signing last summer, now looks as though he has put his partying behind him, as he gets down to business and looks to impress for both club and country next season.