The Premier League champions are in over in Houston, Texas in the United States ahead of their first friendly against Club America at the NRG Stadium.
The 26-man squad, which does not include Ilkay Gundogan, Phil Foden, Aymeric Laporte and John Stones, have been taking part in indoor and outdoor training.
The heat has been sweltering outside and so Guardiola thought he'd help out his £100 million signing and cool him down after a gruelling session.
He dumped a bit of H20 on Grealish's trademark locks, which were yanked by Atletico Madrid defender Stefan Savic last season.
There was a squeal from the former Aston Villa captain, while new signing Erling Haaland couldn't help but laugh.
In terms of the actual session, Haaland and fellow new striker Julian Alvarez were in fine form during the shooting drill.
In footage posted by the club's official Twitter account, the double act showed no mercy in front of goal, slotting past a helpless Ederson on numerous occasions.
At one stage, the Brazil international looked a tad stressed as he watched the ball nestle into the back of the net, time and time again.
Fans really felt for City's goalkeeper, with one commenting: "This is a four minute video of Ederson getting dunked on".
Prior to jetting out, City's stars were in for a surprise when they were paid bizarre compliments by "the President of the Greeters Guild".
The eccentric character, masterfully played by comedian Troy Hawke, baffled Grealish by telling him he had a “fabulously symmetrical face” and produced gold when he said the phrase,"You are a tremendous Nordic meat shield. Have at it!” to Haaland.
Featured Image Credit: Image: Manchester City
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