The major moves this summer in Europe's leading leagues ahead of the transfer window closing on Tuesday.
The ball deflected in off the inside of the England midfielder's left leg from close range after a driven cross by Gabriel Jesus flew across the face of the six-yard box.
The coming season, though, looks to be a four-team race for the title, even if things could change dramatically by some late movement in a transfer window that closes on Aug. 31.
After training with his new team-mates for the first time on Friday, Grealish replaced Sam Edozie in the 65th minute and looked lively in his cameo appearance.
Whether he makes his City debut is an open question, having just joined the English Premier League champion on Thursday.
The 25-year-old Grealish signed a six-year contract with manager Pep Guardiola's squad.
Grealish, who has four years remaining on his Villa contract, scored six Premier League goals for Villa last season and provided 10 assists.
Bukayo Saka's penalty was saved by Gianluigi Donnarumma as England suffered a heartbreaking loss at Wembley.
Manager Gareth Southgate has been able to regularly change his team, with a plethora of attacking talent at his disposal.
For all the experience in Germany's side compared to the youth of England, it was World Cup winner Thomas Müller who squandered a chance to equalize in the 81st minute
The Aston Villa captain has shone in the Premier League this season, sparking rumours he could be set for a big money move to champions Manchester City.