watch carefully
watch closely
watch intently

They stood on the side of the road in a group, intently watching the street.

The other people in the office were still intently watching the television set.

There were many who had been high school players, watching intently.

He watched intently, and a moment later saw it again.

But it's not only the Eye who is watching intently in this book.

He just stood there intently watching the door of the prison.

He was intently watching something which moved at the door rent.

He watched intently, as though looking for some movement from within but there was none.

Anna stopped for a moment across the street, watching intently.

He looked into the eyes of the women, who intently watched their guest.