Problem saving associated models

I want to save data from User(parent model) when creating/editing a Shop
(child model).

My models:
    class User < ActiveRecord::Base
      has_one :shop, :dependent => :destroy

    class Shop < ActiveRecord::Base
      belongs_to :user
      accepts_nested_attributes_for :user #!!!!!!!!!!!!
My Shop controller:
    class ShopsController < ApplicationController
        def new
            @shop =
            #@shop.user = current_user

    def create
        @shop =[:shop])

        @shop.user = current_user
        respond_to do |format|
            flash[:notice] = t(:shop_created)
            format.html { redirect_to(@shop) }
            format.xml { render :xml => @shop, :status => :created,
:location => @shop }
            format.html { render :action => "new" }
            format.xml { render :xml => @shop.errors, :status =>
:unprocessable_entity }

Shop page:
    <% form_for @shop, :html => {:multipart => true} do |f| %>
        <%- f.fields_for :user do |user| %>
            <%= user.text_field :name, :live => true %>
        <% end -%>
    <% end -%>

All examples that I found about saving associated models are when saving
from User (parent) N children ( my Shop model). In those cases I
understand where define accepts_nested_attributes_for.

My case is inverse.

Q: How can I save User data when submitting on Shop form ?