New Yorkers Boo Bill de Blasio as he Throws Out Pitch for Mets (VIDEO)

"Everyone knows that Giuliani was a Yankees fan."

No, they weren't happy to see him. And they couldn't have made it any clearer or yelled it any louder.

New York Mayor de Blasio was booed at Citi Field on Monday, even before he had a chance to throw out the first pitch.

Throwing from the front of the pitcher’s mound, de Blasio threw a strike on the outside corner of the plate to Mets starting catcher Travis d’Arnaud. But fans booed again as he walked off the field.

De Blasio, a proud Boston Red Sox fan, donned a Mets cap and jersey with a No. 6 on it in honor of 1960s-era Red Sox player Rico Petrocelli.

“He’s trying to do too much too soon. He should learn the job first, then make changes,” said Eddie Facenta, 38, of Queens. “He doesn't represent a New York team. Everyone knows that Giuliani was a Yankees fan.”

He doesn't represent New York either.