And Sterling doubled the advantage with 16 minutes when he waltzed through an almost static Tottenham defence and turned the ball past Michel Vorm.
Victory was wrapped up in stoppage time when Tottenham failed to clear their lines after a series of shots were blocked and Diaz popped up to make it two goals from two games with a simple tap in.
It was Walker's first match against Spurs since joining City from Mauricio Pochettino's side and his former manager played down the fact that fans booed the full-back.
Mauricio Pochettino the head coach / manager of Tottenham Hotspur gives the ball to Kyle Walker of Manchester City during the International Champions Cup 2017 match between Manchester City and Tottenham Hotspur at Nissan Stadium on July 29, 2017 in Nashvi
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“I totally understand. Fans showed they are disappointed with the situation but the Tottenham fans love him really.
“He spent nine years at the club. It is not personal. It is not a big issue. It is only to show him they were disappointed he left.”