De Bruyne scored one goal and made another as Manchester City finished their tour of Asia with a 3-1 win over Yokohama.
Belgium midfielder put City ahead with a ferocious shot before Keita Endo leveled after Claudio Bravo had denied Marcos Junior.
However, the champions of Premier League took control when De Bruyne fed Sterling to score his fourth tour goal.
Guardiola, who named a strong starting line-up featuring £62.8m club record signing Rodri, said afterwards his side needed “time” as they prepare for a season in which they hope to win a third consecutive title for the first time.
City start their Premier League campaign on 10 August against West Ham, and Pep said: “Many of the basics are good but we need more games to take the best conditions. It was an incredible test for us, incredibly demanding because of the conditions and the quality of the opponent.”