The two Mercedes led the way out to start the session on a bright sunlit day before Alonso and then Piastri topped the early times, just hours after Alpine had confirmed that Franco Colapinto was to remain with them next year.
Guardiola, who arrived at the Etihad in 2016, said Liverpool were the ideal opponents for his landmark game on Sunday as they had been his biggest rivals in England.
The Scots have never beaten New Zealand in 32 attempts over the past 120 years, with their best results two Murrayfield draws, 0-0 in 1964 and a 25-25 thriller in 1983.
Genge added: "I just made it clear to the boys that, although these people grow up on beaches throwing a rugby ball about and they're lovely people, they are very nasty to play against.