As Jesus drew nearer, Zacchaeus saw that he

wasn't able to see Him because He (Jesus) was
surrounded by the crowd and also because he
(Zacchaeus) was "small in stature."

Zacchaeus was determined to see Jesus. He
wasn't able to get through the crowd so he ran
ahead and climbed up into a sycamore tree.

Then he waited as Jesus and the crowd went
by.